Watford to Croxley Link (proposed successor to the Metropolitan Line Extension ('MLX') and 'Croxley Rail Link')

Three Rivers District Council supports the concept of a Metropolitan Line Extension (also called 'The MLX', and originally named 'the Croxley Rail Link'), which was a proposed extension of the London Underground Metropolitan line, to connect Croxley Station to Watford Junction.

The MLX scheme is now discontinued and since Summer 2021 Hertfordshire County Council has been leading a group (including Watford Borough Council, Three Rivers District Council, Network Rail and Transport for London) to develop a successor scheme, the Watford to Croxley Link (also called 'W2CL'). For more information visit the County Council website here Watford to Croxley Link

The former Metropolitan Line Extension scheme was promoted by London Underground in partnership with Hertfordshire County Council and Network Rail but the initial works were not progressed after 2018 (see the end of this page for updates or for background information visit the MLX page on Wikipedia). Three Rivers District Council and Watford Borough Council were also committed to this project as it would have delivered important benefits to their local communities by:

  • Improving access to public transport for local residents (more than 2,500 households would be within 10 minutes walk of the two new stations)
  • Creating better connections between Watford and Croxley Green, with new routes to Watford General Hospital, Croxley Green Business Park and other Industrial Estates, which would increase access to employment opportunities for local people
  • Providing access for Metropolitan line passengers to West Coast mainline National Rail links from Watford Junction station

If you are interested in the role of Three Rivers District Council, please contact Transport & Projects at 01923 776611 or email

If you have any questions about the former Metropolitan Line Extension scheme, please refer to Transport for London (known as 'TfL', or London Underground) using the following contact details: 

Phone: 0343 222 2424 (24 hours)
Post: London Underground Community Relations, 5th floor, Palestra, 197 Blackfriars Road London SE1 8NJ

Transport for London has not announced that the Metropolitan Line Extension project has been cancelled, but it provided the following update on the 25 January 2018:

“We have always been keen to see the Metropolitan Line Extension progress and the Mayor presented the Government with a practical proposal to find a solution to the funding gap and cost risk. We remain open to helping assist the Department for Transport in finding alternative schemes that may be more affordable. 

“We are currently delivering one of the world's largest programmes of transport investment, including building the Elizabeth line and modernising Tube lines and stations. Huge improvements to the frequency and reliability of services are being delivered on more than 40 per cent of the London Underground network, including the Metropolitan line.” 

Further information

  • After taking on the Metropolitan Line Extension from Hertfordshire County Council, TfL undertook a detailed review to establish the true cost of the project.
  • Following this extensive work we estimate that to complete the extension, we would need to more than double the funding commitment we have already made.
  • The most recent estimate (from February 2017) of the final cost of the MLX is £357.8m. This is £73.4m higher than the current funding package, and doesn’t take into account the accountability for cost risk on the project beyond that estimate.