High Quality Content by WIKIPEDIA articles! The A1 is the longest numbered road in the UK, at 410 miles (660 km). It connects London, the capital of England and the United Kingdom, with Edinburgh, the capital of Scotland. It passes through and near Highgate and North London, Hatfield, Stevenage, Letchworth, Peterborough, Grantham, Doncaster, Leeds, York, Gateshead, Newcastle upon Tyne and Berwick-upon-Tweed.