The A40 has changed significantly in some locations since it was first classified as A40 in 1922. This article describes the 1923 route, and other significant changes since then. The map extract is zoomable and navigable and highlights the 1923 route of the A40.
When road numbers were first allocated, no roads in the City of London itself were classified. Consequently, the A40 started at the edge of the boundary between the cities of London and Westminster, just east of the A5200. Later on, it was extended back along Holborn, Cheapside and Poultry to terminate at Bank, meeting the A3, A11 and A501.
Today, the A40 runs as far as St Martins Le Grand, where the only other classified road is the A1 and the two roads start on each other. None of the A40 inside the Inner Ring Road is signed with its number.
Marble Arch - Denham
The original route of the A40 west from Marble Arch went via Bayswater Road, Holland Park Avenue, Shepherd's Bush Green and Uxbridge Road. In 1951, it was rerouted up Wood Lane and onto the former A403 along Western Avenue as far as Denham, where it rejoined the original route. The old road was renumbered the A4020.
The A40 originally met the A418 east of Wheatley at a T junction. When the first section of the M40 was opened, it ended at a temporary terminal that ran back onto the A40 mainline. The current junction layout dates from 1991 when the M40 was completed, and involves the A40 taking over a short section of formerly unclassified road to meet the A418 in a different location.
Ross on Wye - Abergavenny
The Ross on Wye Eastern Bypass opened in November 1985 and diverted the A40 away from the town and along the former A449 Northern Bypass (built concurrently with the M50) to the junction with the A49.
The original 1922 route of the A40 ran along what is now the A49 and along the B4521 to Abergavenny. It was re-routed via Monmouth in 1935, taking over a section of A48 as far as Raglan, followed by a section of B4234 and A471 . The re-routing extended the A49 by about a mile.
Llandovery - Llangadog
The A40 originally ran south of its current line along what is now part of the A4069, rejoining its original route west of Llangadog.
St Clears - Canaston Bridge
In 1922, the original route of the A40 ran from Blewgyd along the now unclassified road, through the centre of St Clears along the now B4299 and A4066, then along what's now the eastern end of the A477 between St. Clears and Red Roses. It then ran along the current B4314 through Narbeth to Canaston Bridge and the junction with the A4075.
From here, the A40 was a little further south of the current A40, taking the now unclassified road, joining the existing A40 in a small section near Llain. The route passed through the villages of Pont-y-Fenni and Pen-y-Coed before heading into Whitland on the now B4328. To the west of Whitland, the route took it along West Street, then onto the road now used by the Civic Amenity Site. The route then crossed over the railway and along now disused road to the Carmarthenshire/Pembrokeshire border.
Further along, the A40 then went along the now unclassified road through Pengawsai before turning north and around Cwmmau Hill on the edge of Tre-wern Wood. The route then went along the unclassified road rejoining the A40. At Robeston Wathen, the route went along the now B4314 before rejoining the current A40 route at Canaston Bridge
In 1994, the Whitland Bypass was constructed at a cost of £8 million. The road started east of Black Bridge on the original A40, then running north of the town before rejoining the A40 at a new roundabout just west of Llain Cottage.
1998 Trunk Roads Review
The section of the A40 paralleled by the M40 between London and Oxford had already lost its trunk status; however, following the publication of the 1998 paper A New Deal for Trunk Roads in England. further sections of the A40 were detrunked. Firstly, the section through Oxford in 2002. Next to follow was the remainder of the Oxfordshire Council section in 2003 (to the border with Gloucestershire Council. Two years later, in 2005, the section in Gloucestershire from the Oxfordshire border to the M5 was detrunked.
A further detrunking occurred in 2009, from the Gloucestershire/Herefordshire Council border to Ross-on-Wye; however, the section through Gloucestershire did not follow suit, and ten years later there is still therefore a small gap in the trunk road between Gloucester and Ross!
In 2011, the Robeston Wathen Bypass was constructed between Penblewin and Slebech Park at a cost of £41.4 million.