The original A1 route was designated by the Ministry of Transport in 1921, following the medieval Great North Road from Central London through Barnet, Potters Bar[?], Hatfield, Welwyn[?], Stevenage[?], Baldock[?], Biggleswade[?], Sandy, St Neots[?] and Alconbury[?], then joining the route of a Roman road, Ermine Street, as far as Colsterworth[?]. The route was modified in 1927 when bypasses were built around Barnet and Hatfield.
wikipedia.org dumped 2003-03-17 with terodump