British Road Numbering Scheme

Britain has a long history, and has many ancient roads[?] and trackways dating back to the Roman occupation and before. With the advent of the car and the huge expansion in the numbers and standards of roads, as well as the introduction of a national Highway Code, a coherent numbering scheme was developed, which is still in use today.

The road numbering system in England and Wales is based on a radial pattern centered on London. Scotland has an extension of the scheme based on the centres of Glasgow and Edinburgh.

Main trunk routes from London have single digit numbers, starting with the A1 which heads due north. The numbering continues sequentially in a clockwise direction, thus:

• A1 London to Edinburgh (The Great North Road)
• A2 London to Dover
• A3 London to Portsmouth
• A4 London to Bristol (The Great West Road, or Bath Road)
• A5 London to Holyhead (Watling Street)
• A6 London to Carlisle

These radials are supplemented by two-digit codes which are routes that are slightly less important (but may still be classified as trunk routes). These routes are not all centred on London, but as far as possible follow the general principle that their number locates them radially clockwise from the associated single digit route. For example, the A10 (London to Cambridge) is the first main route clockwise from the A1, the A11 (London to Norwich) is the next, and so forth. Some of the more important ones are:

• A11 London to Norwich
• A12 London to Colchester
• A23 London to Brighton
• A30 London to Exeter
• A38 Birmingham to Plymouth
• A40 London to St Davids[?]
• A41 London to Birmingham
• A46 Newark to Bath
• A66 Manchester to Leeds

The system continues to three and four digit numbers which further split and criss-cross the radials. Lower numbers originate closer to London than higher numbered ones. Knowing the number of the road you are on will give you a rough idea of where you are geographically once the system is understood.

"B" roads are routes which have lower traffic densities than "A"roads. The classification has nothing to do with the width or quality of the physical road. B roads follow the same numbering scheme as A roads, but almost always have 3 and 4 digit designations.

Motorways[?] came to Britain much later than the established routes and the numbering system was already in place. Therefore the motorways are designated "M" roads and are numbered to match the existing main radials which the motorways in general follow.

Some ancient routes, such as Roman roads, travel for great distances and have a single modern number for the majority of their length (e.g. the A5 for the Roman road Watling Street). Others, such as the pre-Roman Icknield Way[?] and the Roman Fosse Way are nowadays rather patchy and where a modern road exists, are numbered according to the local scheme.