Replaced for 6 miles (9.7 km) between Popham and the Bullington interchange by the A303 trunk road southwest of Basingstoke. A trunk road west of Exeter. Previously went via A343, Salisbury Road (old A343), B3042 (old A303), A3057, London Road (old B3400), B3400, and city streets (old A33) between Lopcombe Hill and Basingstoke, but this was changed as part of a renumbering of roads in the area.
Most of the section between Oxford and Solihull is arguably the A44 and the A3400 however its modern course ends northeast to join the M40 from which the northern part of the road can be accessed after one junction of the M42 motorway. A trunk road to Oxford and between Stafford and Stoke on Trent.
In two parts. 1. The London Inner Ring Road at Grosvenor Place to the Victoria one way system. 2. Victoria Street, half of Parliament Square and then Bridge Street (Westminster Bridge), followed by part of Westminster Bridge Road (which replaced part of the A23) and finally St George's Road (one way (north-west)) past St George's Cathedral, Southwark).
A303 was previously used for the road from County Hall, London to Wandsworth, which was renumbered to the new A3036 so that the number could be used on the current route which replaced the old A3036, the original A3079, and parts of other roads.
The road has been dubbed "The A three-one-queue" owing to frequent peak-hours' heavy congestion. Part of its course ran from Hatton to Harlington, London across where Heathrow Airport is instead of its present course past Cranford more directly to north-east Hayes and districts further north including Harrow. Its middle section is officially known as The Parkway
Exists in two parts: one from Knightsbridge to the junction with the A4, North and South Circular Roads at Chiswick Roundabout, and the other from the north end of Kew Bridge to East Bedfont. The section in between is part of the South Circular Road
Renumbered when the Hindhead Tunnel opened in July 2011 having been formerly part of the A3. A333 was previously used for the road from Winchester to Cosham until 1994 when it was downgraded to B3335, B3354, and B2177.
A341 was previously used for the road from Winchester to Lopcombe Corner. The section west of Stockbridge became part of the A30 which was rerouted, while the remaining section became part of the A272 (now B3049) at the same time that the current A341 was created.
Previously continued southeast to Winchester; this section was changed to an extension of the A3057 and the new B3420 (part now the A272) as part of a renumbering due to the creation of the current A303.
Ran from A360 to the Stonehenge visitor centre (became C506 in 2017). On 24 June 2013, the section the Stonehenge visitor centre to Stonehenge was closed to public traffic and the section from Stonehenge to the A303 was dug up and no longer exists. Previously, the road continued west to Heytesbury via what is now the A360 and B390, and before the current A303 was created, the road continued east via the current A303 to Andover.
A346 was previously used for the road from Collingbourne Ducis to the A303 south of Shipton Bellinger; this became part of the rerouted A338 in a road renumbering in the area, while the A346 number was reused on the old route of the A345.
A355 was previously used for the road from Sherborne to Blandford Forum (the western portion became part of an extended A352, the eastern portion became part of an extended A357, and the middle section was renumbered the A3030 to discourage through traffic)
Route passes through Taunton and Chard in Somerset. Between Taunton and Ilminster, it provides the main link between the A303 and the M5. Route previously went southeast from Ilminster via what is now the A303 and the A3088 to Yeovil; the route was changed south of Ilminster to the current routing as part of a renumbering due to the creation of the current A303.
The section between Beckhampton and the A4289 in Swindon was renumbered the A4361 to discourage through traffic, and the section through Swindon is now A4289, Wood Street, B4289, Shrivenham Road, Stratton Road, and B4006. Through traffic should use the A4, A346, and A419 between Beckhampton and Swindon. At 195 miles (314 km) is the longest 3 digit A road in the UK. Before the North Devon link road opened, it went along unclassified roads to South Molton, and then northeast via what is now the B3227.
Previously a road between Yarnbrook and Chippenham. Now part of the A350. It was also proposed for the North Devon link road between Barnstaple and Bampton (the file typoed as "Bamford"), but the North Devon link road was rerouted through Tiverton and opened as part of the A361 instead.
Formerly continued north to Uffculme concurrent with the M5 and west to Tiverton via what is now A361, this section became part of its current routes when the freeway extension west of Tiverton was completed. Before the freeway was built, the A373 went west from Honiton to Uffculme via what is now the B3181 spur, B3181 (old A38), A38, A361, Lower Town, Turnpike, High Street, Post Hill, and Blundell's Road. Earlier, the road was routed on what is now South View Road and Willand Road from Willand to Halberton, but this became part of the B3391, while the A373 was concurrent with the A38 north to Uffculme and west on the old A373 spur to Halberton as shown above. Earlier the road continued east to Charmouth via the current A35 (then the A35 went west via the current A3052). Originally, the A373 went west to Ilfracombe, but that section became part of an extended A361.
Runs through Union Street, Plymouth. Originally followed the current A38 between these points (though one section became the B3413 when the A38 bypass was built), while the A38 followed the current route; these routings were swapped later, moving these routes to their current routes. A374 was previously used for the road from Donyatt to Colyford; this became part of the A358 as part of a renumbering due to creation of the current A303.
A378 was previously used for the road from A379 south of Exeter to the A38 (now A3015) in Pinhoe (became part of rerouted A38 (now the north spur of the A379), and the rest was declassified (became the B3182 shortly after that, now Old Rydon Lane), and the northern section became part of the B3181 (now Clyst Road, Sidmouth Road, and Moor Lane).
A392 was previously used for the road from Truro to northeast of Redruth; this became part of an extended A390 (which was later rerouted north), and the A392 was reused on the current routing as an upgrade of part of the B3279.
Previously ran entire length of Torbay Ring Road but rerouted into Torquay (former A380) and along former A379 between Torquay and Paignton. Concurrent with A379 between Torquay and Paignton. Section past Paignton Zoo formerly part of A385.
A3036 was previously used for the road from South Petherton to A344 (now destroyed) near Stonehenge, which became part of the new A303, while the number was reused as a renumbering of the old A303. See also: Albert Embankment
Formerly part of the A31. Before this, the A3090 was allocated to the road from the A31 through Winchester to the A33; this became the B3040 and an extension of the B3047, and the A3090 was reused on the current route.
In the City of Westminster: Sloane Street, Sloane Square, Chelsea Bridge Road, Chelsea Bridge; in the London Borough of Wandsworth: Chelsea Bridge, Queenstown Road (including Queen's Circus); in the London Borough of Lambeth: Queenstown Road, Cedars Road