B roads in Zone 4 of the Great Britain numbering scheme

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.

First used from Slough to Chalfont St Peter; this was upgraded in the 1920s to a portion of a rerouted A332.

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

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.

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.

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.

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).

Originally ran in Birmingham from the A455 (now A34) New Town Row to the A41 Camp Hill.

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.

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

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 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 Swansea to Port Eynon along the Gomer Peninsula.

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.

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.

Likely classified at the last minute (probably early 1923), as the other B442x roads are on Anglesey.

Despite surviving the 1935 renumberings, the route is now unclassified and one-way eastbound.

Next used from the A429 Fosse Way west of Chesterton to Kemble Airfield (now Cotswold Airport).

Number also appears in Wednesfield on online maps before 2009, but this is a typo for the B4484.

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.

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.