How the Motorways were Numbered

Panic stations - 11 June, 1959

Government departments do not make decisions quickly!

C. H. Wykes of the Road Traffic Division notes a problem, and tries to hurry the process along in this memo address to the Divisional Road Engineers (who were the heads of the geographical Divisions which were part of the Ministry's decentralized structure):

It has been decided that the numbering of motorways will be the responsibility of Road Traffic Division.

The signposting of the London - Birmingham Motorway is now a matter of some urgency and its numbering is clearly an essential feature of this signposting. It is desirable, however, that for the purposes for numbering the London - Birmingham Motorway should be considered not in isolation but in conjunction with all other motorways now proposed.

For this reason I should be grateful if you would let me have, by say the end of next week, a list of all motorways coming within the purview of your Division, no matter how remote in time these may be or how early the stage of planning reached. By "motorways" I mean all roads, including bypasses and county roads, such as the Stretford - Eccles Bypass, to be built to motorway standards and subject to motorway regulations. Any cases where the latter point is doubtful should be included in the list and indicated as such and in all cases it will be helpful if the approximate route could be shown on the list. Maps would be particularly helpful if these were available but they are not essential.

Some urgency? Some urgency? The opening of the London - Birmingham Motorway is only a few months away...

A new proposal - 7 July, 1959

C. H. Wykes writes:

It is necessary that we should bring to a head what is to be done about numbering motorways. We have had a road-numbering system for many years - A for Trunk and Class I roads and B for other classified roads - and the system serves a number of useful purposes, enabling routes to be simply identified, signposted and followed and to be so shown on road maps. Professional drivers make great use of the system and I do not think that it is a matter of very great moment that some private motorists prefer to work on names alone.

After consultation with Highways Engineering and the Highways Divisions I recommend that Motorways should have a coherent numbering system of their own - in any case, they could hardly be assimilated to the system as all the single numbers and nearly all the 2-figure numbers have already been used. The obvious prefix is M.

The system we propose would be modelled on the A system i.e. with London as a centre and going clockwise from the motorway to the north as a starting point, the numbers from 1 to 6 should be allocated. The numbers 7, 8 and 9 should, as in the A system, be reserved for Scotland even though we are not aware of any Scottish motorway plans at this stage.

The double figure numbers would be reserved on the principle that M.10 to M.19 would be available for the sector between M.1 and M.2, M.20 to M.29 for the sector between M.2 and M.3 - and so on. Sixty-six numbers would thus be available and these should be adequate for all foreseeable needs in England and Wales without recourse to any 3-figure numbers.

Where a motorway was merely a by-pass on a recognised continuous route, such as A.1, it would not be given a separate M number but, in order to make clear its motorway status and that the special motorway regulations applied to it, the letter M would be added in brackets to the existing route number e.g. A.1(M). This would avoid chopping and changing of numbers along such routes.

The result of applying such a system to current plans would be the appropriate numbering of the London - Yorkshire Motorway as M.1, with provision for extension still further north as required. M.2 would be reserved for any possible Channel Ports Motorway, the Medway Towns Bypass meanwhile becoming A.2(M) and the Maidstone Bypass A.20(M). M3 would be reserved for a motorway in the direction of Portsmouth - Southampton, starting with the Exeter Radial. M.4 would be applied to the South Wales Radial. The remaining single figure numbers would not be required for radials and could therefore, continuing clockwise, be applied to the Bristol - Birmingham Motorway - M.5 and the Penrith - Birmingham plus Dunchurch Bypass - M.6. The Preston Bypass was numbered M.6 in advance and although under these proposals it should initially have been A.6(M), I see no reason to make any change from M.6 pending the ultimate completion of the whole route.

If approval can be given to this general system to govern motorway numbering, there should be scope for fitting in all foreseeable developments for may years to come - and we can proceed, at once, with the proper numbering of the London - Birmingham sections of M.1 and M.6.

The copy of this memo held in the National Archives has some wonderful handwritten notes at the bottom in several different sets of handwriting, including the following comments:

Noted. The Brighton Radial will presumably be M.21 (or M.23?) on this basis. 30/7/59


I have spoken to Mr. Wykes and pointed out that the Dunchurch Spur is not now expected to be continued to the Birmingham - Penrith Motorway; it should not therefore be numbered M.6 but M.12 or something of that sort. I have also suggested that some consideration be given to using a single number for the Bristol - Birmingham and Birmingham - Penrith Motorways.

This, therefore, is the first mention of the "sector" system of numbering. More will be said about this one over time...

Map of proposal

A counter proposal - 10 July 1959

Not everyone at the Ministry agreed. Indeed, there appears to be two factions at this point. Whilst they agree on the numbering in some places, in others there is disagreement...

B. A. Payne:

Meeting to discuss Motorway numbering. 3 July, 1959.

The following points were agreed and were to be put forward for a decision:-

1. The numbers 7, 8 and 9 which were used in Scotland should be reserved for the use of Scottish Motorways.

2. The prefix "M" should be used for Motorways.

3. The numbering of major motorways should approximate to the "A" numbering at present used e.g.
M.1 - the London - Yorkshire Motorway
M.2 and M.3 - reserved
M.4 - London - South Wales Motorway
M.5 - Birmingham - Bristol - Exeter Motorway
M.6 - Birmingham - Penrith Motorway

4. The numbering of spurs from the Major Motorways should fit into the new system with two digits, the first being the number of the Motorway from which the spur originates e.g.
M.50 or M.55 - Ross Spur
M.11 - Spur to Doncaster Bypass

5. Special Road bypasses to existing Trunk Roads should not be given an "M" number but might be shown on directional signs with an "M" after the road number viz.:
Stevenage Bypass - A.1(M)
Doncaster Bypass - A.1(M)
Medway Motor Road - A.2(M)
Maidstone Bypass - A.20(M).

6. Where these bypasses are later to be joined as a complete Motorway, e.g Maidenhead and Slough Bypasses later to become M.4 should carry in the interim stage A.4(M). The Preston and Lancaster Bypasses will be numbered as M.6 as this number has already been given to the Preston Bypass.

7. All other Motorways which are phased for years beyond the present 63/64 programme should be fitted into this procedure.

The "tree" system of motorway numbering makes its first appearance. It won't be its last!

Notice the mention of Scottish Motorways here. Scotland took over its own trunk road system from the Ministry in 1956, so the Ministry had no juristiction there. We'll return to the Scottish system later.

A decision is made - 30th September, 1959

The Preston Bypass has been open for nearly a year, and what will become the M1, M10 and M45 are now only two months away from opening.

C. H. Wykes drafts a memo which includes the following paragraphs:

The Minister intends that a broadly similar system [to the all-purpose network] should apply to the numbering of motorways. England and Wales will be quartered by the London - Yorkshire Motorway, a possible Channel Ports Motorway, the Exeter Radial Motorway and the London - South Wales Radial Motorway, which will be numbered M.1 - M.4 respectively. M.5 will be reserved for the Bristol - Birmingham Motorway, M.6 for the Penrith - Birmingham Motorway (and its eventual extension to join the London - Yorkshire Motorway north of Crick) and M.7 - M.9 for any motorways in Scotland. Two figure numbers will be reserved for spurs and for motorways lying within the sectors bounded by the single-number motorways.

Now that's more like it!

The system described in the previous paragraph will apply to long-distance motorways. Where, however, a motorway is merely a by-pass along an existing route such as the Doncaster Bypass along Route A.1, it will not be given a separate M number, but in order to make it clear that it is a motorway and that motorway Regulations apply to it, the letter M will be added in brackets to the existing route-number - e.g. A.1(M) for the Doncaster Bypass. This will preserve the continuity of the route-number of long-distance all-purpose roads. Generally speaking by-passes that are eventually linked to form a continuous motorway will preserve the existing route-number (plus M in brackets) until they are so linked.

With these principles in mind, the Minister has now allocated numbers to that part of the London - Yorkshire Motorway (including the St. Albans By-pass), together with the spur to Dunchurch and the Dunchurch By-pass, due to be opened on 2nd November. That part of the St. Albans By-pass and of the London - Yorkshire Motorway which extends from its junction with the London - Birmingham Trunk Road (Route A.41) at Aldenham to its junction with the Coventry - N. Tempsford Bridge Trunk Road (Route A.428) at Crick will be known as Route M.1. The eastern arm of the St. Albans By-pass from its junction with the London - Holyhead Trunk Road (Route A.5) at Park Street to its junction with Route M.1 will be Route M.10, and the spur from Route M.1 at Watford Gap (Northants) to Dunchurch, together with the Dunchurch By-pass, will be Route M.45.

33 days from the expected opening of the M1, and a decision is finally reached on what to call the darned thing! The memo continues:

The Minister also confirms that notwithstanding the principles set out in paragraph 4 above the Preston Bypass, which has been known since it opened as Route M.6, will retain that number.

Oh good! The Ministry shows sense when confronted with someone else being forced to take the lead, and didn't try to force it to change to A6(M).


Part 3 - Proposals Fleshed Out >>

How the Motorways were Numbered


Part 1

Part 2

Part 3

Part 4

Part 5


Thanks to Jonathan Winkler, Chris Marshall and Mark Dillon for their help towards the production of this feature.