One hundred years ago Britain’s main roads weren’t numbered because they didn’t need to be. Cars had yet to take over the world, so most important roads still had names from the era of the horse and cart. Most were named after the town at the other end London Road was a favourite or the direction in which they travelled such as Great North Road.

But then motor transport started to get popular and in 1921 the newly-formed Department of Transport decided that all of Britain’s major roads should be numbered.

As was said ‘all roads lead to Rome’, but at the Department of Transport, most roads lead to London.

Civil servants selected six particularly important roads leading out of London (most starting close to the Bank of England) and numbered them A1 to A6 starting clockwise from the north, these were as follows:

A1 London to Edinburgh (409 miles, originally the Great North Road)

A2 London to Dover (77 miles, originally Watling Street)

A3 London to Portsmouth (74 miles)

A4 London to Bath (103 miles, originally the Great West Road)

A5 London to Holyhead (270 miles, originally Watling Street)

You might have thought that the remainder of Britain’s roads were numbered fairly haphazardly, not so, it works like this:

To number the roads, Great Britain has been divided into nine sectors, six of which radiate in clockwise order from London, and the remaining three similarly from Edinburgh. Sector I includes all the roads situated between roads A1 and A2, and so on clockwise for the remaining sectors.

Note: an exception occurs between road A2 and the estuary of the Thames which is part of sector II and not sector I. All roads take their initial number from the sector in which they start, eg A12 and A17 start in Sector I, note that a road does not necessarily terminate in the same sector in which it begins. The commencement of a road is determined by the end of it which would be reached first by the hands of a clock radiating from London.

In honour of the fact that the Ministry of Transport was formed in 1919 and exactly 100 years ago, they were completing their task of numbering the country’s roads, and that the first five arterial roads started in central London, I’m ‘calling over’ in the manner of The Knowledge. All Knowledge ‘Runs’ start or finish anywhere within a six-mile radius of Charing Cross, so I’m going to try to describe the first 6 miles of these roads as if I’m on an Appearance testing my knowledge of London to become a cabbie.

A1 London to Edinburgh

This 409-mile road begins at the unprepossessing Aldersgate outside the old Museum of London, but this wasn’t always the case. The A1 used to begin outside St Paul’s Cathedral, following an old coaching road north up the grandly named St Martin’s-le-Grand, that was before the IRA came along, causing City authorities to erect ‘the ring of steel’ in the mid-1990s.

The A1 now starts a few yards past an unstaffed security checkpoint at a shadowy characterless roundabout. A circular brick island rises in the centre of the roundabout. The A1 heads north from this lonely spot, unlabelled, unsigned, unnoticed.

F Aldersgate Street
F Goswell Road
R Islington High Street
F Upper Street
Comply Highbury Corner
L/By Holloway Road
R Tollhouse Way
L Archway Road
L & R Bakers Lane
B/L Aylmer Road
F Lyttelton Road
F Falloden Way
B/L North Circular Road
B/R Great Northern Way

5-mile ends at approximately Five Ways Corner with the opportunity to join the M1 for a faster journey north.