The A1, also known as the Great North Road, is the longest numbered road in the United Kingdom, at 410 miles (660 km). It connects London, the capital of England, with Edinburgh, the capital of Scotland. The numbering system for A-roads, devised in the early 1920s, was based around patterns of roads radiating from two hubs at London and Edinburgh. The first number in the system, A1, was given to the most important part of that system: the road from London to Edinburgh, joining the two central points of the system and linking the UK's (then) two mainland capital cities. It passes through or near north London, Hatfield, Welwyn Garden City, Stevenage, Baldock, Letchworth Garden City, Biggleswade, Eaton Socon, Buckden, Peterborough, Stamford, Grantham, Newark-on-Trent, Retford, Doncaster, Pontefract, York, Wetherby, Ripon, Darlington, Durham, Gateshead, Newcastle upon Tyne, Morpeth, Alnwick and Berwick-upon-Tweed.

Baldock is a historic market town in the North Hertfordshire district of Hertfordshire, England. The River Ivel rises from springs in the town. It lies 33 miles (53 km) north of London and 14 miles (23 km) north northwest of the county town of Hertford. Nearby towns include Royston to the northeast, Letchworth and Hitchin to the southwest and Stevenage to the south.