Originally ran along the north side of Trafalgar Square; later upgraded to a loop off the A4. The section along Trafalgar Square is now pedestrianized and the remainder is part of the A4.

To the East, through Westbourne Park Road. Crosses Portobello Road.

Originally ran from Willesden to Neasden. Upgraded to Class I status as the A4088 in the mid-1920s.

First used from Slough to Chalfont St Peter; this was upgraded in the 1920s to a portion of a rerouted A332. Reused along old B473 from Beaconsfield to Amersham when the B473 was rerouted to Hazelmere, but became the B473 (now A355) again in 1935.

Originally ran from Stoke Poges to Farnham Royal; it was renumbered as a spur of the B473 in 1935. Now part of the B416.

Originally ran from Boxmoor to Leighton Buzzard (now A4146, A4012 and B440).

Originally ran from Crowmarsh Gifford to Benson. Extended south via North Stoke to the B479 in Goring in the late 1920s. The section north of Crowmarsh Gifford (including the entire original section) became part of a rerouted B479 in the early 1930s and the section of old B479 between Goring and the A42 at Streatley became a portion of the B4008. This became a portion of an extension of the B4009 in 1935.

Originally ran from Oxford to Stadhampton. Renumbered as a western extension of the B480 in 1935.

Next used in 1925 along an old section of the A38 to the east of Norton. Appears on maps up to 1934, but not on 1936 or 1937 maps. Downgraded to a C-road by the 1940s and is now little more than a farm track.

Also used in Warwickshire between Binley and Cross in Hand. This was previously the B4114, then upgraded to the A4114 in the 1940s and renumbered to the A427 in the 1960s and had the B4027 number by the 1990s, probably for continuity, but because the number was in use elsewhere, it was renumbered to the B4428 in the 2000s.

First used from the A42 (now A44) in Woodstock to the A423 (now A4260) at Sturdy's Castle. Declassified in the mid-1920s due to completion of the A4095, which ran parallel to the B4028.

Originally ran from the B4027 at Enslow to the B4030 west of Bicester. Like many of the B402x roads, it was upgraded to the A4095 in the mid-1920s, however it did not follow Akeman Road between Kirtlington and Chesterton but followed the next road north. The section along Akeman Road was declassified instead.

Originally ran along Newbridge Road in Bath. Upgraded to a portion of the A4 in 1935.

Originally ran from Warmley to Fishponds. In the 1935 renumbering, the section from Warmley to Staple Hill was renumbered to B4427 (now A4175) and the remainder to B4465. The southern section was split in two by the A4174 and is now unclassified and closed to through traffic.

Originally ran along Colston Street and Jamaica Street in Bristol. Renumbered as a western extension of the B4051 in 1935.

Originally ran from Wotton-under-Edge to Symonds Hall. Renumbered as an eastern extension of the B4058 in 1935.

Originally ran from Wotton-under-Edge to Cam. Renumbered as a northern extension of the B4060 in 1935.

Originally ran near Dursley, cutting the corner between the B4064 and B4066 (later A4135). Renumbered as a portion of a new B4066 in the 1935 renumbering.

Originally ran between Tetbury and Cambridge. Upgraded to the A4135 around 1930.

First used between Cirencester and Stroud. Due to its importance, it was upgraded to Class I status as the A4116 (now A419) in the mid-1920s.

Next used from The Quarry to the A38. Renumbered as a western extension of the B4066 in 1935.

Used a third time from Hinckley to Sapcote, despite the number being out-of-zone. Renumbered to the B4669 (still out-of-zone) in the 1990s (along with many other roads in Hinckley) when the A47 northern bypass was built.

Originally ran along Gloucester Road in Cheltenham, connecting Lansdown railway station to the A40 and A4019. Later renumbered as a counterclockwise extension of the B4075 and is now part of the B4633.

Originally ran from Kingsmead to Thelsford, cutting the corner between the B4086 and A429. Now unclassified, as the A429 does the job of the B4088.

Originally ran in Redditch; its precise route has not been definitely established as the route never showed up on any maps, but it likely ran along Church Green East. Declassified early on and is now pedestrianized.

Originally ran along Priory Road in Warwick. Now part of the A445 one-way system.

The road is briefly reprised in Birmingham City Centre as a continuation of the A34 until it meets with the B4114 and A47 in Birmingham City Centre. Also used for the section of former A41 from junction with A4540 to A4400 Snow Hill Queensway.

First used along Balsall Street in Balsall Common, connecting the A446 to the B4101. Became a portion of a rerouted A4023, but was downgraded back to the B4101 (not B4105, the B4101 having taken over the new route) in 1986 due to completion of the M42.

Next used in 2015 along Broad Street in Coventry. May have been short-lived; little is known about this route. It is listed in a 2015 FoI request response from Coventry Council as well as on other 2011 documents, but it does not appear on a September 2016 revision of the OS VectorMap District map. The route is now unclassified.

Originally ran from Binley (near Coventry) to North Kilworth, but was extended in the early 1930s to the southern extension of the A50 (formerly B568, now A5199) at Bosworth Lodge. Around 1935, the original route was upgraded to the A4114 (later A427); the extension hung on for a few more years as the B4111 before being renumbered to the B5414 as it was out-of-zone. The section between Coventry and the A5 was downgraded back to Class II status as the B4027, despite being a duplicate (this was corrected to B4428 in the 2000s). With the impending A14 in the 1990s the eastern section was renumbered to A4303 between the A5 and M1 and A4304 on the section to North Kilworth; both numbers are out-of-zone.

Originally ran along Suffolk Street in Birmingham. Upgraded to Class I status early on (the current number was in use by 1932), although due to its short length it is unknown what number it received. Later upgraded to a portion of the A4400 Queensway and is now the A38.

Originally ran along Navigation Street in Birmingham. Due to its short length, it is not known how long the B4129 number lasted; a map showed the route as Class I, but with no number (it was the A4166). Now unclassified after all traffic was routed out of the center of Birmingham.

Originally ran in Birmingham from the A455 (now A34) New Town Row to the A41 Camp Hill. Upgraded to Class I status, with all except the southern end becoming the A45 by the mid-1940s. Now part of the A4540.

Originally ran from Queslett to Sutton Park. Upgraded to a portion of the A4041 in the 1970s.

This was previously used for the following roads in Wolverhampton: Garrick Street, Market Street and Princess Street. After Dudley Street (the original route of the A459) was pedestrianized in the 1960s, these streets formed a rerouted A459 until all roads in the city centre were declassified in 1986 due to completion of the Inner Ring Road. Another B4158 appeared in Dudley on OS maps between the 1950s and 1970s. Perhaps due to the duplicate number, it was renumbered to B4588.

Originally used on a route connecting the A461 to the A449 (now A491) in Amblecote. Upgraded to Class I status, becoming the A4102 in 1925.

Originally ran along Chapel Street in Lye, cutting the corner between the A58 and A4036. Declassified after the 1960s.

Originally ran from Little Malvern to Upton-upon-Severn. Upgraded to the A4104 before 1930.

Originally ran from Bosbury to Stony Cross. Renumbered to a portion of the A4154 after World War II, but downgraded soon after to the B4220 (the B4218 number was already in use elsewhere).

Originally ran from Monmouth to Huntley; was the lowest numbered Class II road in Wales. Due to its importance, it was upgraded to Class I status early on, becoming the A4136 in the late 1920s.

Originally ran from Cinderford to Elton. Renumbered as a portion of the A4151 in 1935.

Originally ran from Old Forge to Harewood End. Upgraded to Class I status as the A4137 in the late 1920s.

Originally ran from Monmouth to King's Thorn. Renumbered as an extension of the A466 in the mid-1920s.

Originally ran from Raglan to Llanvihangel Gobion. Became a portion of a rerouted A40 in 1935 (old A40 became the B4251).

Originally ran from Blaenavon to Govillion as the northern continuation of the A4043. Renumbered as a portion of a northern extension of the B4246 in 1935.

Originally ran from Llandough to Penarth; was not connected to the rest of the UK classified network until 1935, when it was renumbered to A4160.

Originally ran from Llandaff to Llantrisant. Became the A4119 by the mid-1920s.

Originally ran in Caerphilly from the B4263 in Penyrheol to the A468 (now B4600). Renumbered as a spur of the B4263 in 1935.

Originally ran from Llantwit Major to Cowbridge. Renumbered as a southern extension of the B4270 in 1935.

Originally ran from Bridgend to Llantwit Major. Renumbered as a western extension of the B4265 in 1935.

Originally ran from Ystrad Rhondda to Llantrisant. The section from Ystrad to Tonyrefail was upgraded to the A4093 in 1924, but a year or so later, the entire route was upgraded to the A4119. Much of route now unclassified or part of the B4278.

First used between Cymer and Glyncorrwg. Upgraded to the A4108 in 1925, then renumbered as the northern end of the A4063 in 1935. Now unclassified.

Next used from Crynant to Banwen as a continuation of the new A4109. Became a portion of an extended A4109 by 1932.

Originally ran along Oystermouth Road and Victoria Road near the Swansea seafront. Later became the start of the B4290 and is now part of the A4067.

Originally ran from Swansea to Port Eynon along the Gomer Peninsula. Upgraded to Class I status in the mid-1920s, becoming the A4118.

Originally ran from Ystalyfera to Sennybridge. Renumbered to the A4067 and A4068 in 1935; one section is now the B4599.

Originally ran from Gurnos to Brynamman. Upgraded to Class I status in 1935, becoming the A4068.

Originally ran along Market Street in Llanelli; too short (only 100 yards) to appear on maps and may have never appeared on any maps at all as it was decommissioned by 1935. Th route was still Class II in the 1960s, but as a spur of the B4304. The original southern end is now gone, lost under Argos.

Also appears in the circa 2002 DfT Card Index as "Reserved for Gwndwn goyn - Parcllyn Road" This is generally assumed to be a route from Park Avenue to Parc Y Llyn in Aberystwyth, but for some reason never used.

Originally ran from Llan Ffestiniog to Conwy via Betws-y-Coed. By 1932, the southernmost section had become a portion of a rerouted B4408 to Congl-y-Wal and the A496 from there to Blaenau Ffestiniog. By 1939, the B4408 was decommissioned, with the A496 extended over it further to Betws-y-Coed and the section from there to Conwy renumbered to the B5106. Sections became the A4108 and A5110 by 1956, but the ex-B4408 is now the A470 from Llan Ffestiniog to Betws-y-Coed and B5106 north of there; the section just south of the A5 is now unclassified.

Originally ran along Queen Street in Carmarthen. Likely classified at the last minute (probably early 1923), as the other B442x roads are on Angelsey. Despite surviving the 1935 renumberings, the route is now unclassified and one-way eastbound.

First used from Berkeley to Sharpness. In the 1935 renumbering, it was recommended that the route be extended to the A4135, but this never happened; the B4066 was extended west to Sharpness and the B4428 was declassified instead.

Next used from the A429 Fosse Way west of Chesterton to Kemble Airfield (now Cotswold Airport). Became a portion of a rerouted A429 in the 1960s.

Originally ran from Marian's Inclosure to Tutshill. By 1932 the first section into Coleford became an extension of the B4431 while the remainder was renumbered to B4228. Later renumberings rerouted the B4228 to take over the section north of Coleford.

Number also appears in Wednesfield on online maps before 2009, but this is a typo for the B4484. March End Road is now part of the U99 and Alfred Square Road is possibly unclassified.

Originally ran from Wolvey Heath to Cross in Hand. Declassified in the mid-1970s due to completion of the M69. The ex-B4455 crosses the current B4455 at Cloudesley Bush.

Originally ran from Bow Street to Capel Dewi. Upgraded to Class I status in 1935, becoming the A4159.

Originally ran along Sutton Road in Kidderminster. Now part of the A4535.

Originally ran from Brimfieldcross into Brimfield itself. Upgraded to Class I status, becoming the A4105 in 1971, but has been declassified again due to completion of the A49 Brimfield bypass.

Originally ran in Stratford-upon-Avon from Evesham Place to the A34 Birmingham Road. Upgraded to Class I status in the 1970s as the A4134, but within 10 years this was renumbered to a portion of the A4390.

Originally ran from Stoke Mandeville to Aston Clinton. Downgraded to the C142 in 2003 when Aston Clinton was bypassed.

Originally ran from Brecon to Bishop's Meadow. Upgraded to Class I status around 1960, becoming the A4062. But when the A40 Brecon bypass opened in 1980, it returned to Class II as the B4602 except for the southernmost section, which was declassified.

Also appears on the former A459 north of Dudley. This is a typo for the B4588.