Unallocated numbers

For whatever reason, some road numbers in the United Kingdom and Ireland have never been allocated. In most cases, especially in the Scottish zones, this is because there were more numbers available than were required. Others are currently unallocated because they were previously in use and have not yet been reallocated.

Perhaps the most notable missing number - and certainly the most asked-about - is the M7 within Great Britain. This appears to be a glaring omission of an important number, but it occurs because of the Scottish motorway numbering system, which requires numbers to be selected according to the A-road that the motorway follows. No motorway follows the line of the A7, and therefore no M7 exists.

Below is a listing of numbers that are unallocated for either reason.

Great Britain

Never allocated

Motorways (1 and 2 digits)

• 2 zone: M21, M22, M24, M28, M29
• 3 zone: M33, M34, M35, M36, M37, M38, M39
• 4 zone: M43, M44, M46, M47
• 5 zone: M51
• 7 zone: M7, M70, M71, M72, M75, M76, M78, M79
• 8 zone: M84, M86, M87, M88, M89
• 9 zone: M93, M94, M95, M97, M98, M99

3-digit A roads

• 7 zone: A773, A774, A777, A782-799
• 9 zone: A992, A995, A996, A998, A999

3-digit B roads

• 1 zone: B147
• 2 zone: B246-249, B293-299
• 3 zone: B320, B328-340, B342-348, B391-399
• 4 zone: B417-424, B426-429, B431-438, B441-449, B492-499
• 5 zone: B527, B532-539, B541-549, B592-599
• 6 zone: B602, B604-629, B631-639, B642-644, B646-649, B696-699

3-digit motorways, 4-digit A roads, 4-digit B roads

There are many examples - too numerous to list.

Previously allocated

Motorways

Numbers appeared on the ground

• 1 zone: M10
• 4 zone: M41
• 5 zone: M531
• 6 zone: M63
• 8 zone: M85

Numbers that didn't appear on the ground (including unbuilt in italics)

• 1-zone: M12, M13, M14, M15, M16, M17, M19, M100, M110, M111
• 2-zone: M270, M272, M273, M274
• 3-zone: M30, M31
• 5-zone: M52, M59
• 6-zone: M64, M68, M600, M601, M650
• 8-zone: M81, M82, M83

3-digit A roads

• 1 zone: A108, A115, A150, A175
• 2 zone: A241, A263, A266, A276, A279, A294
• 3 zone: A344, A364, A398
• 4 zone: A434, A440, A455, A471, A492
• 5 zone: A524, A564, A568
• 6 zone: A604, A613, A622, A648, A668
• 7 zone: A715, A729, A731, A732, A733, A734, A740, A742, A744, A748, A750, A753, A754, A757, A758, A764, A765, A767, A769, A776, A778
• 8 zone: A802, A805, A825, A840, A842, A843, A845, A852, A853, A854, A856, A859, A860, A864, A869, A870, A871, A874, A881, A892, A895
• 9 zone: A906, A920, A925, A927, A931, A936, A943, A946, A951, A954, A958, A968, A973, A974, A976, A979, A983, A987, A988, A997

3-digit B roads

• 1 zone: B103, B107, B110, B114, B115, B116, B117, B123, B124, B128, B129, B130, B131, B132, B133, B141, B162, B163, B169, B171, B190, B196
• 2 zone: B200, B201, B225, B231, B233, B239, B241, B244, B252, B254, B257, B267, B268, B287, B292
• 3 zone: B301, B303, B307, B308, B309, B314, B315, B341, B354, B355, B356, B357, B359, B362, B366, B370, B371, B379
• 4 zone: B403, B407, B424, B457, B458, B459, B460, B463, B464, B468, B473, B475, B476, B479, B484, B492
• 5 zone: B503, B505, B508, B513, B516, B522, B523, B528, B529, B553, B554, B555, B557, B558, B559, B561, B563, B564, B566, B567, B577, B580, B583, B584, B588, B591
• 6 zone: B650, B654, B657, B665, B666, B673, B674, B675, B677, B678, B681, B685, B687, B688, B689
• 7 zone: B716, B728, B760, B770, B772
• 8 zone: B807, B809, B811, B813, B820, B831, B848, B850, B854, B856, B859, B860, B868, B889
• 9 zone: B904, B911, B926, B958, B963, B982, B984, B988, B989

4-digit A roads, 4-digit B roads

There are many examples - too numerous to list.

Republic of Ireland

Never allocated

National Primary Routes

• 3 series: N34, N35, N36, N37, N38, N39
• 4 series: N41, N42, N43, N44, N45, N46, N47, N48, N49

National Secondary Routes

• 8 series: N88, N89
• 9 series: N90, N91, N92, N93, N94, N95, N96, N97, N98, N99

Previously allocated

• N32, N57, N64, N66, N79