100 years of road numbers

Published on 01 April 2023

They’re everywhere and we take them for granted, but it’s time to put them centre stage. We’ve now had road numbers for a hundred years.

A hundred years is a long time for anything on the road network. Most of us think of motor vehicles as being something recent enough that the history is measured in decades. But we’re now starting to see the centenaries of the early landmarks in motoring history, and 2023 is the turn of the UK’s first road numbers.

Today is the start of a season of celebrations here on Roads.org.uk to mark one hundred years of finding our way with As, Bs and numbers.

Celebrating 100 years of road numbers

They were first created by the Ministry of Transport back in the early 1920s, originally as part of an exercise to work out which roads were busiest and needed funding for maintenance and improvement. The Ministry’s civil servants must have done a decent job of devising a system, because much of the work they did then still guides our journeys today.

The one and only book

We're here to celebrate a centenary, but how do you fix a point in time and say ah, yes, here: this is when road numbering began?

You can’t. Arguably the first road numbers were chosen in 1921, and other significant moments in the years-long process of numbering happened throughout 1922.

However, we’ve chosen 1 April 1923 because that was the date the Ministry of Transport published its List of Class I and Class II Roads and Numbers, the official document containing all of the brand new road numbers in Great Britain. It was intended to be the moment road numbers were formally made available to the general public in full.

A rare surviving work-in-progress numbering diagram from about 1921. Click to enlarge
A rare surviving work-in-progress numbering diagram from about 1921. Click to enlarge

If you've never heard of this document, and never seen a copy for yourself, there is a reason for that.

The Ministry had been consumed with the business of classification and numbering for several years by 1923, and it was a project with origins before the First World War. Its completion would give the road network structure, make it navigable, and provide a sound empirical basis on which funding could be allocated and improvements could be designed. It was the first move in the modernisation of the road network, and it's no understatement to say that it was the start of a new era for transportation in this country.

The cover of List of Class I and Class II Roads and Numbers. Click to enlarge
The cover of List of Class I and Class II Roads and Numbers. Click to enlarge

Thoroughly infused with pride and excitement for this incredible achievement, the Ministry ordered a print run of 5,000 copies of their new booklet, and intended to release new versions periodically when the list of roads was revised.

For their part, however, the British public did not appreciate just how momentous this occasion was, and for some reason a slim volume containing dry lists of roads, classifications and numbers did not seem to capture their imagination. Of the 5,000 copies printed, fewer than 2,000 were sold, and in 1925 it was withdrawn from sale. No official list of roads was ever made available to the public again.

Of the 1,927 copies sold, few are thought to survive today, and most remaining copies are in libraries. If you wish to turn back the clock and inspect Britain's road numbering system as it stood in 1922, when it was pristine and almost perfect, your best option is the faithful transcription of the whole book that is made available by SABRE. (SABRE's wiki is, by the way, the modern home of UK road numbering, maintaining the most complete list of current numbers in existence, as well as an exhaustive history of changes and amendments at every point in their history. SABRE also makes the special Ordnance Survey MOT Maps available, which show road numbers through the 1920s and 30s.)

Still, while List of Class I and Class II Road Numbers may not have made waves in its time, it did decisively mark the moment that the architects of the UK's road numbering systems first made the whole of their work available to the public. It was a hundred years ago today.

Numbers for all

You can't keep an idea that good to yourself. Great Britain's numbers were completed in April 1923, but the same concept of classifying roads and applying numbers was being followed across the islands.

Northern Ireland was the next to create its numbered road network, with all its A- and B-roads being published across two editions of the Belfast Gazette in December 1923. The Isle of Man followed, with its A- and B-roads published by the Tynwald in February 1926, and then Jersey at an uncertain date in the years that followed.

They're everywhere! Here's the A1 and the A2, but not the ones on the mainland. Click to enlarge
They're everywhere! Here's the A1 and the A2, but not the ones on the mainland. Click to enlarge

Since then a great many numbers have changed, and some of the more rigid principles of the system have been relaxed or even abandoned - but a visitor from the Ministry of Transport of 1923 would still be able to look at a map of the UK today and see a system they recognised. They'd even see a lot of roads they recognised: despite all the changes there are plenty of road numbers still in situ today from that original 1923 allocation.

What that time travelling visitor might be surprised to find is just how ubiquitous their numbers have become.

Uptake was not initially very rapid, partly because people were used to navigating without numbers, but also because it took years for numbers to be consistently seen on signs, and even longer for map publishers to add numbers to all their maps.

Today, though? They’re everywhere. The Great North Road is a well known and ancient route, but take a sample of the population and you’ll find more people know it as the A1. You can describe somewhere as being “within the M25” instead of saying it’s in London. Weather reports talk about conditions along “the M4 corridor”. In sport you’ll find local rivalries referred to as the “A420 derby” (Swindon vs Oxford), the “M11 derby” (Bishop’s Stortford vs Harlow Town), the “A62 derby” (Huddersfield vs Oldham) and dozens more. The radio soap opera The Archers even has a map of the area in which its stories are set, complete with a whole host of fictional A- and B-roads.

Celebrating 100 years

This post is the start of a season of celebrations here on Roads.org.uk. And we're starting with a long overdue update to an old friend.

For many years we’ve had a long feature in our Articles section about road numbers. If you visit now, you’ll find it’s been extensively rewritten, expanded and improved, with all sorts of new detail and new illustrations to explain the way the UK’s many numbering systems work (and sometimes don’t work), and how we came to have the numbers we use today. It’s the place to go if you want to find out how numbering in the UK works, and even if you’ve read it before, it’s been so thoroughly overhauled that we highly recommend another look.

Elsewhere on

In the coming weeks we’ll be adding more new posts that will explore some of the other real oddities and unexpected stories about road numbering, and hopefully prove once and for all that even the driest corners of this very niche subject can be completely fascinating, if you just know where to look.

Until then, a very happy numbering centenary to you all, from here on the borders of zones 2 and 3.


Richard 2 May 2023

Can anyone explain why the A6 doesnt cross the border? The A1, A4(AFAIK) and the A5 all do. And then of course there the A66!!

There was a suggestion in the early 1920s, when numbering was a work in progress, that the A6 should continue to Edinburgh, but it doesn’t because it would mess up the Scottish zones: if the A6 formed the boundary between zones 6 and 7, what would the A7 do?

The A4 doesn’t cross any national boundaries, it ends at Avonmouth, and when originally created it stopped at Bath. 

I wasnt aware that the A4 didnt go in to Wales, always thought it did. Thanks for that.

The main route through South Wales was the A48 before the M4 took over. For those that didn't know, many parts of the M4 were originally numbered A48(M) until the rest of the motorway caught up with them.

I think only one was the A48(M), which was the Port Talbot bypass - all the others opened as M4 at the outset.

Richard 5 May 2023

There are quite a few problems with the numbering. Heres a couple and they do involve the 6 series, other than the A66. The A69 runs from Carlisle to Newcastle, but the M69 runs from Leicester to Coventry! And of course as has been commented on an earlier post the A601 being the ring road in Derby but the A601(M) being in Lancashire!

Nothing wrong with the A69 and M69 following different routes. Have you read our guide - linked above - about how motorway numbering works?

Richard 6 May 2023

I must admit I havent. I was under the impression that motorway numbering followed A road numbering. So I assumed that logically that the M69 would be near the A69. And this point was raised in the Daily Telegraph motoring section getting on for 30 years ago. And on the motorway numbering isnt the M5 wrongly numbered?

No, because (in England, Wales and NI) motorway numbering is entirely separate to A-road numbering! Otherwise, how do you explain M50, M49, M32, M606… the list goes on. See the guide here.

And does this explain why the M6 stops at Carlisle? People will remember that when the A74 was being upgraded there were signs up saying was doing to be called the M6. I wonder if a civil servant realised that the number couldnt cross the border?

To my understanding, it was always the plan that the A74(M) at least, if not also the M74, would have been renumbered to M6 after completion of the final link. However, that plan belonged to the Westminster MoT - whereas when transport (including road numbering) was devolved to the then Scottish Executive, they simply dropped the renumbering plan. As far as I know, no-one has ever managed to get a particular reason out of them, they just... didn't do it. I believe the point gets raised in the Scottish Parliament every now-and-then to at least extend the M74 number to the border, but the relevant Scottish Ministers are always tight-lipped about it.

Also, to say that the M6 number "couldn't" cross the border I think is a bit much. Road numbering in the UK is not law and the systems that exist are frequently bent or outright ignored. If the MoT/Scottish Executive had wanted the M6 to run to Glasgow, there was absolutely nothing to stop them. Personally I think it would have made sense, so you don't end up with the absurd situation we have now where you have 3 different numbers for the same continuous road. Actually, now I think about it, with the completion of the A14(M) (well, planned to be (M) anyway), we now have a single continuous motorway-standard road that runs from London to Glasgow, but uses five different numbers to get there! M11 -> A14 -> M6 -> A74(M) -> M74. (by continuous I mean you don't have to 'turn off' at any point, the main carriageway carries on each time even as the number changes.)

The plan to extend the M6 number to Glasgow came several decades after responsibility for trunk roads was devolved to Scotland, so it wasn't strictly a Westminster plan. It was created by the Scottish Office in about 1992, but when devolution happened and the Scottish Executive was created a few years later, the new government seemed not to consider renumbering a priority. When (twice) a question was asked about it in the Scottish Parliament, the answer was simply that there were "no plans" to change the road's number. The SABRE Wiki includes a very thorough history of the whole thing here.

It's absolutely true that there's nothing to say the M6 couldn't cross the border. Roads can and do cross the border between Scotland and England. If the Scottish Government ever did decide to renumber it M6, there would be nothing stopping them.

To say the A14 is continuous motorway standard is stretching things. There are still some places, eg between Huntingdon and Kettering where right-turning traffic has to cross the central reservation and the opposite carriageway, and parts of the section from the A1 to the M6 is bendier than your average motorway. But it's certainly much improved.

Ive looked at the guide on motorway numbering. And Ive spotted an anomaly and its to do with the M62. Surely as it starts in the 5 zone it should start with a 5?

Yes, it should, but when it was first created it started east of the M6. It was then extended west later on. It was presumably thought more important to retain a well-established number than to carry out a disruptive renumbering exercise just to preserve the purity of the system.

The western end of the M62 really should be the M57 - along with the M602 linking up with the A57(M).

There's evidence on Pathetic Motorways to suggest it would have been M52. And honestly that would be a better number.

Richard 30 May 2023

And heres another anomaly. There is a road in Edinburgh called the western approach road it is a dual carriageway and is built on an old railway line. The last I knew it had no roads number. Anyone know any more about it?

Roger 1 July 2023

Why is the M3 classed as going from east to west instead of south to north, eg Southampton to London.

Classed as east-west where? Our Motorway Database page refers to northbound and southbound. But it’s really a diagonal, as much north/south as east/west, and since we don’t refer to roads as running “northeastbound” or “southwestbound”, an approximation has to be made.

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Picture credits

  • Archive diagram of work-in-progress road numbering is extracted from MFQ 1/708.
  • Image of front cover of 1923 road numbering booklet is from "1922 Road Lists", SABRE Wiki.

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