Counties 1 Herts/Middlesex (formerly London 2 North West) is a tier 7 English Rugby Union league.

It is organised by the London and South East Division Rugby Football Union and is the top-tier competition for clubs in Hertfordshire and parts of north-west London that traditionally was encompassed by the historic county of Middlesex.

After the restructuring of the English rugby union system ahead of the 2022–23 season, the league was renamed to Counties 1 Herts/Middlesex.

Joining were Brunel University and Ealing Trailfinders 1871, promoted from Counties 2 Herts/Middlesex, together with Fullerians, relegated from Regional 2 Thames.

The cancellation of National 5 South at the end of the 1995–96 season meant that London 3 North West reverted to being a tier 7 league.

However, the introduction of London 4 North West ahead of the 2000–01 season meant that clubs were now relegated into this new division instead of into Herts/Middlesex 1.