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Location Map ( geo)
Cameraicon.png View gallery (39)
From:  Heyford Hill, Oxford (SP529028)
To:  Ryton on Dunsmore (SP371751)
Via:  Southam
Distance:  22.8 miles (36.7 km)
Meets:  A4074, A4142, A4144, A34, A361, A422, A425, A426, B4455, B4453, A445, A5
Former Number(s):  A415, A42
Old route now:  A404, A4130, A4074, A4260, B4098, A51
Primary Destinations
Highway Authorities

National Highways • Oxfordshire  • Warwickshire

Traditional Counties

Berkshire • Oxfordshire • Warwickshire

Route outline (key)
A423(M) Holyport - Maidenhead Thicket
A423 Maidenhead Thicket – Oxford
A423 Heyford Hill – Hinksey Hill
A423 Oxford – Banbury
A423 Banbury – Ryton on Dunsmore
A423 Ryton on Dunsmore – Two Gates
A423 Two Gates - Birkenhead


Today the A423 is a quiet, although primary, road. A far cry from when in its heyday it went through two major cities on route from the A4 near Maidenhead to the A5 near Tamworth.

Oxford Southern Bypass (1 mile)

A small section of A423 survives in Oxford

When the majority of the A423 was downgraded in the 1990s (see below for more details) for some reason a mile of so of the Oxford southern bypass retained the A423 number despite the fact it would make more sense becoming the A4142.

The road starts on the semi-hamburger Heyford Hill roundabout where it meets the A4142 southern bypass and the A4074 (former A423) to Wallingford. It heads northwest, crossing two branches of the River Thames to a roundabout where it meets the A4144 which provides access to the Redbridge park and ride and Oxford city centre. Now heading west, the A423 crosses the Oxford to Didcot railway line to end on the A34 western bypass at a roundabout GSJ.

The road then disappears for the best part of 30 miles (which is longer than the total distance of road numbered A423), reappearing to the north of Banbury town centre.

Banbury to Ryton on Dunsmore (23 miles)

Southam Road, Banbury

Originally the A423 passed by the famous Banbury Cross before heading north. Today it begins its much shortened route from the A422 Southam Road Roundabout about 2 miles north of the town centre. After a short distance running alongside the Oxford Canal and past the former Alcan aluminium factory, a final roundabout allowing access to the recent Hanwell Fields residential development to the west and further industrial units to the east marks the limit of Banbury's urban area.

The next twelve miles of the A423 is a real pleasure, providing you don't get stuck behind a slow lorry or tractor. The road is a fine example of 1950s and 1960s improvement which allows the modern driver to cruise at a happy 60 mph from just outside Banbury to the start of the Southam bypass. The road surface is good and the quality and camber excellent for what is a fairly rural road. After leaving Banbury the road climbs steeply and crosses over the M40 with good views from both north and south, before climbing out of the Cherwell valley towards the Oxford-Warwick county border, and some twenty miles of pleasant rolling countryside.

There is a long, three-mile climb to Mollington before Farnborough Hall (National Trust) is passed on the left and the road climbs further to pass to the right of Windmill Hill (560 ft) and down to cross the main railway line from Banbury towards Leamington and the Oxford Canal (twice) as well. From here the road sweeps down towards Southam, bypassing the village of Ladbroke to the east in the process. Southam itself is also now bypassed on its eastern side, both this and the Ladbroke bypasses were built in the 1980s and 1990s. The bypass itself allows the A423 to meet the A425 which multiplexes with the A423 for about a mile between the first two roundabout junctions of the bypass, whilst the final roundabout marks the start of the A426 heading off north west towards Rugby.

The Fosse Way junction at Princethorpe

Once out of Southam the road strikes due north to meander through more rolling hills, crossing the Grand Union Canal at Long Itchington, and on through Marton to cross the Fosse Way at Princethorpe. The Roman road, B4455, arrives at the village centre and the A423 from the left before doing a little wiggle to head off north east to the A5 at High Cross. The A423 is also crossed at the village by the B4453 Leamington to Rugby road.

From Princethorpe the roads climbs over Ryton Heath before descending and passing a Police Training Centre on the left and then meeting the A445 at a roundabout. Continuing straight over, the road then passes the former site of the Peugeot-Citroen car plant on the right, now just a derelict wasteland however. A simple grade-separated junction then marks the end of the primary A423 route, flowing neatly onto the A45 towards Coventry. Traffic wanting the eastbound A45 should have taken the A445 to reach it.


Original start of the A423 in Oxford

When first numbered in the early 1920s, the A423 started at St Giles, Oxford, on the A42 and ended on the A5 at Two Gates, south of Tamworth. On its way it met the start of the A43 at Kidlington, crossed the A41 in the Banbury area (with a multiplex south of town), the A45 in Coventry (with an even longer multiplex), and the A47 east of Birmingham (with a short multiplex). In 1935 the extension of the A34 north of Newbury led to the A42 from Reading to Oxford being renumbered, with the section north of Shillingford becoming the A423. At the same time the A415 from Maidenhead Thicket to Witney was split into two road numbers, the section east of Dorchester being allocated to the A423. As part of the 1935 renumbering that caused this extension, it was proposed that the A423 actually took over the whole A51 to Birkenhead (although this did not in fact take place). For the next twenty years the A423 connected the principal A4 and A5 roads by an attractive and varied middle England route - a distance of 99 miles.

The description below covers all of the 'heyday' route and includes notes on the road number and other route changes encountered.

Maidenhead Thicket to Crowmarsh Gifford (17½ miles)

In its heyday, the A423 went all the way to the A4 at Maidenhead Thicket
A small dual carriageway section of the former A423 between Henley and Wallingford

If you drive west out of Maidenhead on the A4 today, just before you reach the A404(M) junction you will come to a roundabout at the former eastern edge of Maidenhead Thicket. The 1935 incarnation of the A423 started its journey here. Turn right and follow the unclassified road parallel to the A404 dual carriageway to the hamlet of Stubbings. At this point you are on what was in 1922 the A415 Maidenhead - Witney road. A little further, after bridging the A404 you come to a roundabout at Applehouse Hill, junction of the A403 and A423 before the extension of the Marlow bypass from the Thames valley in the early 1990s. The motorway link south from the A4 to junction 8/9 of the M4 was originally part of the M4 before later being numbered the A423(M) (and became the A404(M) when the rest of the A423 was renumbered in this area).

Take the A4130 across the roundabout and down through Hurley Bottom and follow the south bank of the River Thames to Henley. On the way pass Remenham Hill look out for an attractive milepost by the roadside. After crossing the river by the Winterbrook Bridge, the road - still the A4130 - climbs up out of Henley towards the Chiltern ridge along Fair Mile, through Lower Assenden and Bix (great name!) to Nettlebed. This is the heart of the Chiltern Hills. After a mile or so Nuffield Common is reached, at the watershed and 666 feet above sea level. From here the road descends to near the Thames, but before that, near a place called Harcourt Hill, the modern road sweeps away to the left and makes directly for Wallingford. At this place the A423 once went straight on to the village of Benson. This lane leads to the main gate of RAF Benson.

The Benson diversion

Benson in the 1940s

In the 1930s the A423 ran from Nettlebed down to the Thames at Benson and on through Dorchester-on-Thames to Oxford. Land to the east of Benson was chosen for the site of a new RAF flying station and building work commenced in 1937. It opened in April 1939 as home for 103 and 150 bomber Squadrons. Originally built as a grass airfield, the main road ran along the south side and passed the main entrance at the foot of Beggarsbush Hill. By 1941 it was decided to lay two runways and perimeter track to accommodate the use of larger aircraft. This work, carried out in the spring, severed the road and created a traffic diversion through Crowmarsh Gifford and Preston Crowmarsh. The lanes around the latter village were very twisty, so the Royal Engineers were brought in to build a short bypass on the eastern side of the village. It survives as part of the A4074.

The Benson village bypass

The story goes that in the late 1920s Oxfordshire County Council had enough money left in the roads budget to build a bypass around one village. The choice came down to either Dorchester-on-Thames or Benson, both villages having narrow streets found difficult by modern traffic. The council settled on Benson and the road opened about 1931. Ten years later the bypass became largely redundant when the airfield was extended. Dorchester finally got its bypass fifty years later in 1981.

Banbury to Crowmarsh Gifford (36½ miles)

Starting at Banbury Cross, we head due South, multiplexing with the old A41. We climb a small hill and almost immediately the A361 heads off to our right towards Chipping Norton and eventually Ilfracombe! Heading out through the outskirts of Banbury we pass under the grade separated junction at Bodicote, this is a fairly rare example of a GSJ on a single carriageway road. After a couple of miles we reach Adderbury, the old A41 (now B4100) leaves us at a traffic light controlled junction to our left. This was the point where the A423 regained its number south of Banbury. Incidentally, the section from here to Oxford was downgraded before the section from Oxford to Maidenhead: it is now the A4260.

Near Deddington (now the A4260)

After about 3 miles we enter Deddington, a quaint village with its soft yellow coloured houses. We pass over a junction with the B4031 here, heading off towards Aynho. South of Deddington the road is wide enough for S3, and we climb up Deddington hill, a site of many fatal accidents over the years. There have been small improvements to the alignment of the road here which are still visible. After the North Aston and Duns Tew turn we travel through the only section of Dual Carriageway between here and the outskirts of Oxford. It is a split carriageway with little to tell you the other side is there. The next junction, Hopcrofts Holt, is again traffic light controlled. The Hotel which is named after the junction is on our left. The B4030 crosses us here on its journey from Enstone on the old A34 to Bicester.

The road is narrower but still of a good quality from here onwards. We cross the B4027 a few miles on, but the road isn't signposted. Almost straight away we cross the A4095 from Bicester to Witney. The junction is staggered. The disused branch line to Woodstock passes between the two roads. The bridge has been removed, but the abutments are still there. We pass by Sturdys Castle pub and the turning for Thrupp, a village on the Oxford Canal. The Canal travels alongside for a short while. Once over the main Oxford to Banbury railway line we enter Kidlington and Gosford. The A43 used to start here at a junction in the centre of the town, but was diverted to meet the A34 the next junction down. Once through Kidlington the road used to bear left to meet the A40.

The route through Oxford itself has varied over the years. In 1932 the A423 ran into the city centre, multiplexing with the A34 to Carfax and A40 as far as The Plain, before regaining its number and leaving town along the Iffley Road (now A4158).

When the Oxford Ring Road was initially built the A423 was removed from the city centre. It multiplexed with the eastern bypass (A40 and A4142) to join its old route at Littlemore. However, the final section of the bypass, to the south of the city across the River Thames, rerouted the road again. This section opened as A423 (and still is!), taking traffic to the west of Oxford via the A34.

Heading south from Oxford we travel down the Sandford on Thames bypass. The road again is wide here, enough for S3. It suddenly narrows again when entering Nuneham Courtney. The houses and trees neatly lining the road. This section of the road is now numbered A4074.

Once through the village, we pass an arboretum and arrive at the Golden Balls roundabout. Why it is named this I do not know. We cross the B4015 here. Within a couple of miles we encounter the end of the A415 at Berinsfield. The Dorchester bypass starts here, opened in 1981, and one of the widest single carriageway roads there are, it is easily wide enough for S4 and possibly a narrow S5! Once at the end of the bypass we enter Shillingford, the A329 joins us here from Thame. We continue on into Benson, the road entered the village and followed a different route before the airfield was built (as described above). The road now carries on towards Crowmarsh Gifford on the outskirts of Wallingford. Crowmarsh Gifford was bypassed in 1987 due to its narrow roads and a traffic light junction which was always snarled up. The road now meets the A4130 which takes over the A423 to Henley, and the A4074 continues on down to Reading.

Ryton on Dunsmore to Two Gates (21¾ miles)

Originally, the A423 ended on the A5 at Two Gates. The other side of the crossroads was the A51.

Today the A423 terminates at the GSJ onto the A45 but at its height it continued on through Coventry and beyond. The old road can be followed for most of its length as a pleasant country drive.

Continue along the A45 dual carriageway over the Ryton Bridge and to the next roundabout at Tollbar End. Ignore the signed route and go 'straight on' to the B4110 - the London Road - into Whitley. Turn left at the next roundabout onto the A4082 and at the next roundabout turn north onto to the A4114 'superhighway'. This will take you to the A4053 Coventry inner ring road with its numbered junctions (clockwise, from the north). You can go either way around the city - or through it if you're very brave - but, either way, you'll need to turn off the ring road at junction 9 onto the B4098. This is the beginning of the final stretch, a well made, if rather bendy, 'A' quality road. From the ring road interchange the road climbs a short hill (dual carriageway) past Barrs Hill School before making its way though the suburbs. At the city limits a well made unclassified road joins from the left opposite a hotel. This is Long Lane, it runs back to a roundabout at Brownshill Green and then 'becomes' the B4076 to the old A45 Birmingham Road (now the A4114). The 'B' road was built to serve the nearby Jaguar car plant. I guess the 'B' status wasn't extended along Long Lane to the former A423 in an effort to discourage heavy traffic taking the shortcut.

What is now the B4098 going under the M6

Two miles further along you pass under the M6, just to the west Corley services. From here the road climbs out into the north Warwickshire countryside passing Whitacre colliery a few miles along on the left, and through the small villages of Furnace End (a coal connection?) and Nether Whitacre. You then go under a railway bridge to arrive at a roundabout signed A4097 left, A51 straight on and 'unclassified' right. The roads to the left and right are relatively modern affairs built when the A423 lost its life here and became an extension of the A51 in about 1980. The unclassified road to the right, incidentally, was built principally to serve a couple of collieries which then were subject to McGregor's Axe. It still rates highly as a handy short cut to the A5 / M42 J10.

The old A423, now the A51, wends its last few miles over Dosthill and down to the A5 at Two Gates - so named from the toll gates on Watling Street and on our road at this junction. The road ahead is the A51 into Tamworth and could have become the A423 if changes in 1935 had been different.


Related Pictures
View gallery (39)
A423 south of Princthorpe.jpgFosse Way traffic crossing the A423 at Princethorpe.jpgThe A423, Southam Road, Banbury.jpgSite of Ryton car plant (5) - Geograph - 1698004.jpgHalo - Coppermine - 11363.jpg
Other nearby roads
NCN51 • A34 • A40 • A42 (Reading - Birmingham) • A43 • A44 • A420 • A4074 • A4141 (Oxford) • A4142 • A4144 • A4158 • A4165 • A4260 • B480 • B4014 (Oxfordshire) • B4027 • B4150 • B4495 • B4496 • E05 • Longest Lane • M40 • Oxford Ring Road • T10 (Britain) • T13 (Britain) • T42 (Britain) • T47 (Britain) • T114 (Britain)
A45 • A46 • A427 • A428 • A429 • A444 • A445 • A4023 • A4053 • A4082 • A4114 • A4170 • A4273 • A4600 • B4027 (Warwickshire) • B4076 • B4082 (Coventry) • B4098 • B4101 • B4105 (Coventry) • B4106 • B4107 • B4107 (Coventry city centre) • B4108 • B4109 • B4110 • B4111 (Coventry - Kilworth) • B4113 • B4115 • B4118 (Coventry) • B4428 • B4454 (Coventry) • B4481 • B4544 • Coventry East-West Motorway • Coventry North-South Motorway • Droitwich - Leicester Motorway • E24 • E28 (Birmingham - Ipswich) • E33 (London - Glasgow) • E33 (Northampton - Liverpool) • Holyhead Road • M6 • M45 • M69 • Northern and Western Motorway • Sherbourne Valley Road • T11 (Britain) • T44 (Britain) • T114 (Britain)
A4 • A4(M) • A308 • A308(M) • A330 • A404 • A404(M) • A415 • A416 • A423(M) • A3034 (Maidenhead) • A3064 (Maidenhead) • A3095 • A4094 • A4130 • B3023 (Maidenhead) • B3028 • B4447 • C7722 (Windsor and Maidenhead) • C8711 (Windsor and Maidenhead) • C8733 (Windsor and Maidenhead) • C8750 (Windsor and Maidenhead) • C8752 (Windsor and Maidenhead) • C8753 (Windsor and Maidenhead) • C8754 (Windsor and Maidenhead) • C8806 (Windsor and Maidenhead) • C8811 (Windsor and Maidenhead) • C8812 (Windsor and Maidenhead) • C8813 (Windsor and Maidenhead) • C8814 (Windsor and Maidenhead) • C8815 (Windsor and Maidenhead) • C8817 (Windsor and Maidenhead) • C8820 (Windsor and Maidenhead) • C8821 (Windsor and Maidenhead) • C8822 (Windsor and Maidenhead) • C8823 (Windsor and Maidenhead) • C8825 (Windsor and Maidenhead) • C8826 (Windsor and Maidenhead) • C8832 (Windsor and Maidenhead) • C8835 (Windsor and Maidenhead) • E30 • E105 (London - Fishguard) • EuroVelo 2 • Longest Lane • M4 • NCN4 • T9 (Britain) • T42 (Britain)
A400 • A401 • A402 • A403 • A404 • A405 • A406 • A407 • A408 • A409 • A410 • A411 • A412 • A413 • A414 • A415 • A416 • A417 • A418 • A419
A420 • A421 • A422 • A423 • A424 • A425 • A426 • A427 • A428 • A429 • A430 • A431 • A432 • A433 • A434 • A435 • A436 • A437 • A438 • A439
A440 • A441 • A442 • A443 • A444 • A445 • A446 • A447 • A448 • A449 • A450 • A451 • A452 • A453 • A454 • A455 • A456 • A457 • A458 • A459
A460 • A461 • A462 • A463 • A464 • A465 • A466 • A467 • A468 • A469 • A470 • A471 • A472 • A473 • A474 • A475 • A476 • A477 • A478 • A479(W) • A479(E)
A480 • A481 • A482 • A483 • A484 • A485 • A486 • A487 • A488 • A489 • A490 • A491 • A492 • A493 • A494 • A495 • A496 • A497 • A498 • A499
Defunct Itineraries & Motorways: A403 • A404(M) • A405 • A407 • A423(M) • A430 • A437 • A446(M) • A455 • A464 • A475 • A491

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