Previously allocated to a road from Luton to near Babraham. Became a portion of the A505 in 1935 when it was extended north to the A11; the section through Hitchin and Baldock is now the B656.

Later used for the Gateshead Western Bypass from Birtley to Blaydon. Became part of the A69 early on and then the A1 in the 1990s.^[1]

Number also appears in the DfT Road lists from around 2002 as "Reserved for use for the Kirkumgate - Disforth proposals". Both place names do not exist with these spellings ("Kirkumgate" is probably an archaic spelling for Kirkhamgate and "Disforth" is a typo). The route is likely a descendant of the Kirkhamgate - Dishforth Motorway, a proposal to extend the M1 north between Leeds and Bradford, which later became the A6183, before being rerouted east of Leeds and becoming the M1 extension north of J43.

Later used as a provisional number along the Haslingden Bypass in east Lancashire. It was extended to meet the M65 at J8 in 1985 and was then renumbered as part of a rerouted A56.

Next used from Kegworth to West Bridgford, linking the M1 at J24 to Nottingham; a portion of the route was formally the B679. In 1978, the section west of the A614 was renumbered as a portion of a rerouted A453; the section to the east returned to the B679.

Originally ran from Budby to Worksop. Renumbered to B6005 in the 1970s and much of the route became part of the B6034 in the 1980s except for one section that was declassified.

Originally ran from Stony Middleton to Grindleford Bridge. Downgraded in the 1960s to a portion of the B6521 (the A622 was downgraded at the same time to the B6001).

Glossop

An older routing went from A57 High Street to A616 Bank Street in Sheffield, but was later extended north to A61 when it was rerouted along West Bar. Became part of the A621 by the 1960s and is now unclassified.

Originally ran along Commercial Street in Sheffield, linking the A57 to the A61. Although the road was still classified in the 1990s, it did not have the A6020 number (it was moved to its current route in the 1930s) and had likely become a spur of the A57. Now unclassified.

Originally ran from the A642 to the A61 in Wakefield. The section along Marygate is now part of the A650 and the section along Bull Ring is unclassified, although some maps claim that it is also part of the A650.

Originally used for the northern end of Derby Street in Bolton, linking the A579 to the A568 (now A676). Route is now gone due to redevelopment.

Ran as a loop off of the A1 along the former A1 via through Newark-on-Trent Renumbered to the A616, B6325 and B6326 because there was no need for a Class I road through Newark after the bypass opened in 1990.

Originally ran from A693 in Stanley to A692 in Hobson. Downgraded to Class II status as the B6173.

Originally ran from A686 in Crook Hill to A69 in Haydon Bridge (now Shaftoe Street; bridge demolished). Declassified in the 1960s, probably when the current bridge was built.

The original route went from A62 in Newton Heath via Lightbowne Road to A6104 in Moston; this became part of an extended B6393 by the 1970s.

Originally allocated to a road from A629 north of Sheffield northeast to A61; this became part of a rerouted A61, and the road number was reused on the old route of the A61.

Originally ran along former A58 in Bolton, linking the A58 to itself. Now the western end of the A676.

Originally used in Bolton, possibly allocated in the 1960s alongside the A6145. Probably short-lived as the number was reused slightly further south in the 1970s.

The original A6172 went along Roff Avenue, Park Avenue, and Polehill Avenue in Bedford (it is unknown whether this was signed or even numbered).

Originally proposed as an alternative number for the M1 west of Leeds proposal between Kirkhamgate and Dishforth. Dropped in favor of a route from the M1 to the A1 that ran east of Leeds, eventually becoming the M1 extension.

Ends to a single track road leading to Chapel-en-le-frith