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Location Map ( geo)
Cameraicon.png View gallery (62)
From:  Marylebone, London (TQ270816)
To:  Maidenhead (SU858807)
Via:  Rickmansworth
High Wycombe
Distance:  43.5 miles (70 km)
Meets:  A5, A501, A4206, B411, A4207, B414, B450, B451, A4000, A219, A407, A406, A479, A4089, A4005, A4088, A4127, A409, A4006, A312, A4090, A410, B466, B472, A4125, B469, A4180, A4145, A412, M25, B4442, A4154, A355, A413, B474, A40, M40, A4010, A4155, A308, A4130, A404(M), A4
Former Number(s):  A410, A4090, A416, A415
Old route now:  A4154
Primary Destinations
Highway Authorities

Brent • Buckinghamshire • Harrow • Hertfordshire • National Highways • Hillingdon • Kensington and Chelsea • Westminster

Traditional Counties

Berkshire • Buckinghamshire • Hertfordshire • Middlesex

Route outline (key)
A404 Marylebone - Amersham Bypass
(A413) Amersham Bypass
A404 Amersham Bypass - High Wycombe
A404 High Wycombe - Maidenhead
A404(M) Maidenhead - M4
A404 Burchett's Green - Knowl Hill

The A404 runs northwest from Marylebone, London, to Buckinghamshire via Hertfordshire before then looping southwards into Berkshire. It is one of those, "What were they thinking of?" roads, but when it was originally classified, the road from London terminated in Amersham and the route to Maidenhead was not designated as the A404 until 1935.


Marylebone - Stonebridge Park

Underneath the Westway

The A404 begins in London on the Marylebone Road (A501) as a primary dual carriageway and crosses the Edgware Road (A5) on the Marylebone Flyover and at grade as the slips. It then TOTSOs and spawns London's major western radial, the A40 (Westway). Now, as slip roads, the A404 continues as the Harrow Road through Paddington. Opposite is the end of the Marylebone Road and overhead is the Marylebone Road flyover.

At a large roundabout, Bishop's Road and Paddington Station are on the left and Warwick Avenue and Little Venice are on the right. We following a sign that says Kensal Green A404 straight ahead. Now under the Westway flyover on a dual carriageway, we get a good view of the railway lines coming out of Paddington Station and the goods shed. We dive into an underpass below the Eastbourne Terrace slip roads and emerge at a traffic light junction. Here traffic for the A40 can turn left past Royal Oak station and a nice little tour around the Georgian terraces, while we veer off to the right, rejoin the eastbound traffic and make our way over the Regents Canal, past some tower blocks to Kensal Green.

On the right we have shops and rows of Victorian terraces; on the left, the canal and low-rise flats. We pass the B414 and the B450 and catch a glimpse of Trellick Tower, a onetime eyesore, and now grade 2-listed building, the tallest tower block in the country. We pass along by the final destination of many Londoners - Kensal Green Cemetery, hidden on the left by a high wall. We pass Kensal Green station on the right, meet the end of the A219, cross the West Coast Main Line, pass Willesden Junction station and arrive in Harlesden and its one-way system. We go round the houses and shops, pass the start of the A407 and we catch sight of the first of many inter-war semis on the right. A forest of traffic lights heralds a diamond junction which was built in the early 1990s to cross the North Circular Road (A406).

Stonebridge Park - Chorleywood

Approaching Wembley, we go up a hill to approach a road junction with Empire Way to the right. Built for the British Empire Exhibition of 1924, this road leads to the stadium, the arena and the conference centre. An art deco clock tower stands on a traffic island as we go down Wembley High Street, multiplexing with the A4089. We leave Wembley and turn right at a roundabout where we meet the A4005. We then pass Barham park on the right to pass under a girder railway bridge and into Sudbury. The A4005 disappears to the left and we are now in Watford Road heading almost due north. We pass the end of the A4088 and after the A4127 roundabout comes a large expanse of open land, Northwick Park, and with it the first stretch of 40 mph limit. On the right, we see the large concrete buildings of Northwick Park Hospital, while on the left we see the old village of Harrow on the Hill, with its distinctive church spire. Our 40 limit ends at a roundabout where we meet the A409 and the Metropolitan line. We turn left at this roundabout and head west along Kenton Road, skirting the foot of Harrow Hill on the left and Harrow town centre on the right, the buildings here are a mix of Victorian semis and mirror glass-sided office blocks.

We meet the A312 at a mini-roundabout where we turn right and make the first of four (used to be six before the A404 was rerouted) crossings of the Metropolitan Line. before turning immediately left at a second mini roundabout into Pinner Road past more Victorian houses and shops as we pass through North Harrow. The A4090 disappears left under a girder bridge past North Harrow Station. The roadside properties change to large semi-detached houses with little parades of shops at various road junctions as we enter Metroland, areas of land speculatively developed as housing estates by the Metropolitan Railway during the 1920s and 1930s to encourage the middle classes to leave central London and live in an idyllic, semi-rural setting conveniently close to a railway station.

Pinner Road disappears off to the left; the A404 used to take that route through Pinner until it was rerouted during the early 1980s along King George V Avenue through Pinner park; another 40 mph limit and the only significant bit of dual carriageway on this section. George V becomes St Thomas Avenue leading to a mini-roundabout T-junction with the A410 Uxbridge Road. We turn left onto the former A410 route. The houses around here have become very large and detached some have been rebuilt as flats. The B466 comes in on the left and we swing round to the right and rejoin the original route. The B472 Joel Street, Northwood Hills' high street, branches off left and we continue along Northwood Road and our second encounter with the Metropolitan Line which crosses us on a huge skew truss bridge, by far the biggest railway bridge on the route. Northwood High Street, the A4125, is on the right.

At the top of the hill, we pass into a 40 mph limit. The houses start getting further apart. The Good Life TV series was filmed somewhere around here (although set in Surbiton, some distance away). The B469 turns to the right followed by the A4180 to the left, we breast another hill and pass the rambling site of Mount Vernon hospital whose frontage hasn't changed since I went there for an operation in the mid-1960s. We cross into Hertfordshire just before Batchworth Heath with its distinctive church and crossroads: on the left a lane to Harefield and its world-famous heart hospital and to the right a road to Moor Park and golf course. We go straight on into the green belt and our first stretch of NSL, unfortunately all-to brief as we come to Batchworth village and a 30 limit and signs saying downhill 12% gradient - the steepest on the A404. At the bottom of the hill, we meet the A4145 from Watford at a roundabout.

The A404 then becomes D2 and crosses the River Colne and the Grand Union Canal. The route used to be straight through Rickmansworth but now, at the Batchworth Roundabout, it bears left as S2 Riverside Drive, following the River Colne to meet the A412 at the Ebury Roundabout. The A404 briefly multiplexes as D2 bypassing the centre of the town. It goes under the railway and at the Station Roundabout, it bears left as a D2 for 200m uphill to reach the Royal Masonic School for Girls on the right. Running along the southwestern side of the top of the Chess valley, we reach junction 18 of the M25 motorway. The junction is a signal-controlled half diamond, half parclo, and only really exists because the M25 here is upgraded A405. At this, we had climbed 30m since we left the A412.

M25 - M40

After passing over the M25, we pass through the north of Chorleywood and into Buckinghamshire. After a brief rural section, we reach Little Chalfont, passing under the Metropolitan Line. Continuing adjacent to the line, we reach a mini-roundabout where the A4154, at one time a spur of the A404, heads off under the line in the direction of Amersham-on-the-Hill and we bear left descending to the roundabout on the A413.

There is a short multiplex west along the A413, which bypasses Amersham Old Town, until the A404 reappears at a roundabout by Amersham Hospital. Initially the road continues westwards, passing through a wood near the village of Penn Street, before bearing more southerly and entering High Wycombe. The road descends the steep Amersham Hill signed as 10% with an urban escape lane crossing the railway line to level out in a one-way loop. A404 traffic turns left and then bears right to reach the A40 at traffic lights, where it turns right to run along a D2 as far as the Magic Roundabout, where it rejoins the northbound route of the road. Turning left in a southwesterly direction, the A404 is now dual for a mile or so leading to the M40 J4 and the A4010. We continue south on a new alignment.

M40 - A404(M)

Amersham Hill, High Wycombe
A404, Marlow

This trunk dual carriageway has a roundabout junction with the A4155 and bypasses Marlow. The A404 crosses the River Thames on Longridge Bridge, to enter Berkshire. At the Bisham Roundabout, we meet the A308 and the original route of the A404. Here we experience the lowest-quality part of this section. We turn off the original route, which headed through Burchett's Green to the A4 and join new build from the 1990s that grade-separates the Burchett's Green and The Thicket roundabouts, bypassing the old section of A423. At The Thicket Roundabout, we meet the A4 at a roundabout interchange and gain blue signs.


see main article A404(M)

Much of the A404(M) began life as the A4(M) Maidenhead bypass, which later became part of the M4. Originally, the plans were for a route north of Reading. Priorities changed and it is now the A404(M) and a bypass of Maidenhead on the north-south axis.


In the 1922 Road Lists, the A404 ran only from the A5 at Paddington to the A413 at Amersham. In the 1935 Road numbering revision, the A404 took over the route of the A4090 in Amersham as a spur, since renumbered as the A4154. At the same time, the stretch of the A416 from Amersham to the A4 at Knowl Hill became an extension of the A404.

In the early 1990s, a new link near Maidenhead was built, grade separating the Burchetts Green and The Thicket roundabouts, making a dualled and mostly grade-separated link between the M40 and M4. The A423 and A423(M), which was the main route before was renumbered as A4130 and A404(M) at the same time. The A404/A404(M) route was trunked at this time and the old A404 route through Burchett's Green was declassified.

Handy Cross Interchange was upgraded with a cut through in 2008.

Named junctions

See A404/Named Junctions


Related Pictures
View gallery (62)
A404 Northwood High Street.jpgA404(M) Maidenhead - Coppermine - 6885.JPGRoundabout on Stanley Hill, Amersham (C) David Howard - Geograph - 2633061.jpgLow-rise flats in Little Chalfont (C) Jonathan Billinger - Geograph - 988798.jpgCrendon Street, High Wycombe (C) Rob Emms - Geograph - 2853831.jpg
Other nearby roads
Central London
A Ring • A2 • A3 • A4 • A5 • A10 • A11 • A13 • A23 • A40 • A40(M) (Central London) • A41 • A100 • A200 • A201 • A202 • A203 • A215 • A300 • A301 • A302 • A303 (Vauxhall - Wandsworth) • A400 • A401 • A402 • A500 (Marble Arch - Finchley) • A501 • A1200 • A1202 • A1203 • A1204 (Wapping) • A1208 • A1209 • A1210 • A1211 • A1212 • A1213 • A2198 • A2200 • A2205 • A2206 • A2207 • A3036 • A3200 • A3201 • A3202 • A3203 • A3204 • A3205 • A3211 • A3212 • A3213 • A3213 (Pall Mall) • A3214 • A3215 • A3217 • A4200 • A4201 • A4202 • A4203 • A4205 • A4208 • A4209 • A4801 • A5200 • A5201 • A5202 • A5203 • A5204 • B100 • B101 • B107 • B126 • B128 • B129 • B130 • B131 • B132 • B133 • B134 • B139 • B144 • B200 • B201 • B202 • B240 • B300 • B308 • B309 • B310 • B310 (Thames Embankment) • B311 (Westminster) • B312 • B323 • B324 • B326 • B327 • B400 • B401 • B402 • B403 • B404 • B405 (Trafalgar Square) • B406 • B500 • B501 • B502 • B503 • B504 • B505 • B506 • B507 • B513 • B521 • B522 • B523 • B524 • CS1 • CS2 • CS3 • CS5 • CS6 • CS7 • CS8 • E1 (Old System) • E2 (Old System) • E5 (Old System) • Ermine Street • EuroVelo 2 • Great North Road • Holyhead Road • London Inner Ring Road • Longest Lane • M1 • M11 • NCN13 • NCN4 • RM3 • Watling Street
A40 • A312 • A409 • A410 • A4005 • A4006 • A4008 • A4090 • A4125 • A4127 • A4140 • B358 • B457 • B458 • B459 • B460 • E13 • Longest Lane • M1 • M16 • Ringway 3
High Wycombe
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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