Great Britain road numbering scheme

In Great Britain, roads are given a letter with 1–4 numbers after it. This is how they are named. The letter is the category of the road. There are two main types of categories: motorways (with the letter M) and non-motorways. There are two types of non-motorways: A roads (with the letter A) and B roads (with the letter B). A roads are more important than B roads. There are also a very small number of C roads.

This system only applies to the island of Great Britain. Northern Ireland and other islands have their own systems.

 Motorways (M roads) 

 A roads 
 Single-digit A roads 
In England and Wales, the six A roads with one number are most important roads coming out of London. Starting with the A1 which goes north, numbers go clockwise around London:
 A1 – London to Edinburgh (also known as the Great North Road)
 A2 – London to Dover (the southern part of Watling Street, also known as the Dover Road; though the A2 past Rochester has been replaced by the M2)
 A3 – London to Portsmouth (also known as the Portsmouth Road)
 A4 – London to Avonmouth (also known as the Great West Road or the Bath Road; though this route is not used anymore to travel far since the M4 was built)
 A5 – London to Holyhead (the Northern part of Watling Street)
 A6 – Luton to Carlisle (the A6 first started in Barnet on the old A1)

In Scotland, important roads from Edinburgh have A roads with one number:
 A7 – Edinburgh to Carlisle (though the M74 and M8 motorways now are mainly used)
 A8 – Edinburgh to Greenock (used to link Edinburgh to Glasgow, but it now ends and carries on as the M8  away from Glasgow)
 A9 – Falkirk to Scrabster (first went from Edinburgh to Inverness)

 Other A roads 
Zone 1 A roads
Zone 2 A roads
Zone 3 A roads
Zone 4 A roads
Zone 5 A roads
Zone 6 A roads
Zone 7 A roads
Zone 8 A roads
Zone 9 A roads

 B roads 
Zone 1 B roads
Zone 2 B roads
Zone 3 B roads
Zone 4 B roads
Zone 5 B roads
Zone 6 B roads
Zone 7 B roads
Zone 8 B roads
Zone 9 B roads

 References 

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