South Mimms Services, A1(M) Junction 1

South Mimms is the first stop on the A1(M) and one of the best-known service areas in the country, because it serves two motorways at once. What do you need to know?

Where it is

The services are near South Mimms in Hertfordshire, at Junction 23 of the M25, which is also Junction 1 of the A1(M). They are reached from the junction, so drivers on either motorway, in any direction, can use them. The site was built on Bignell’s Corner, which had earlier held a garden centre, a pub, a hotel, a truck stop and a café.

Who runs it

South Mimms is operated by Welcome Break.

History

• The fuel station opened in December 1986 and the full service area on 24/05/1987.
• Margaret Thatcher officially opened it on 06/06/1987.
• It was the first service area directly reached from the M25.
• The building was destroyed in August 1998 by a fire that started in a deep fryer.

What is there

• A BP forecourt, described at opening as the largest petrol forecourt in Europe, with 27 pumps.
• Food, shops and conference facilities.

The 2019 Motorway Services User Survey placed South Mimms in the top five motorway services in the UK for customer satisfaction.

Traffic around Junction 1

The Department for Transport counted 73,025 vehicles a day on the A1(M) between Junctions 1 and 2 in 2025, and 49,183 on the short length between the A1 and the M25 at Junction 1. For the orbital, see M25 Traffic; for this motorway, the latest A1(M) traffic news.

The next stop

Heading north, the next A1(M) service area is Baldock at Junction 10. See also A1(M) Junctions 1 to 10 and all A1(M) services.

Traffic count figures on this page are from the Department for Transport road traffic statistics, 2025.