Plans to extend the Metropolitan line will no longer be going ahead despite the project being in the pipeline for a number of years.

Richard Harrington offered the £73million shortfall needed to make the project work to Mayor of London Sadiq Khan, but he has refused this offer.

The extension has faced a number of setbacks since the Department of Transport announced proposed funding for the project in 2010, with a funding shortfall being the biggest factor in the scheme facing a doubtful future.

Here is a timeline of everything you need to know about the project so far:

October 2010 – Proposed government funding programme for new scheme known as Croxley Rail Link is announced by the Department for Transport.

September 2011 – Hertfordshire County Council, with support from London Underground and Network Rail, submit Best and Final Bid (BAFB) to DfT.

December 2011 – Dft confirms £76m of central government funding that would finally allow the Croxley Rail Link to go ahead and be up and running by January 2016.

In 2011, the project was expected to be delivered under the management of Hertfordshire County Council at a cost of £116.8m.

February 2012 – Watford Met closure is announced and the public is told two new stations will be re-established on the Croxley Green branch named Cassio-bridge Station and Watford Vicarage Road Station.

The Croxley Rail Link included a number of new stations along the Metropolitan Line

May 2012 – Secretary for State for Transport announces decision to hold an inquiry into the application for a Transport and Works Act Order.

October 2012 – Inspector rules the application for an exchange land certificate in relation to the land at Lavrock Lane in Croxley is no longer required.

April 2013 – Hertfordshire County Council appoint Watford-based Vinci Construction UK Ltd to carry out detailed design.

June 2013 – Start of initial on-site works following the appointment of Watford-based Taylor Woodrow

July 2013 – Hertfordshire County Council and London Underground granted legal powers needed to build, operate and maintain the Croxley Rail Link

January 2014 – Planning applications for the two new stations, viaduct and electricity substation for the Croxley Rail Link submitted to Watford Borough Council and Three Rivers District Council.

September 2014 – Final bid for funding approval for the project sent to the Department for Transport

December 2014 – The plans are approved and construction begins. The scheme is projected to cost £230m.

March 2015 – Hertfordshire County Council designated to lead consortium of local funding partners, including the Hertfordshire LEP and Watford Borough Council, which combined, promise to contribute £128.08m to the total scheme costs. The department for Transport agrees to provide £109.82m and Transport for London will provide £46.5m for the rail link.

August 2015 – Transport for London take over control of the scheme from Hertfordshire County Council.

November 2015 – Croxley rail link secures final funding and is renamed Metropolitan Line Extension.

TfL took over the scheme after costs rose to £280m and the funding deal was agreed between the DfT, TfL and the council.

December 2016 – the plans are left out of the Mayor of London’s travel agenda.

March 2017 – A £50m shortfall is announced leaving the future of the project in doubt.

A Freedom of Information request by The Watford Observer in March last year revealed that almost £130m of taxpayers’ money had been spent on the project.

Before transferring the project to Transport for London in 2015, Hertfordshire County Council contributed £30.9m, Watford Borough Council gave £9.6m and the Hertfordshire Local Enterprise Partnership gave £87.9m

July 2017 - Plans for a new station in Watford were still being amended and updated despite no further funding being put forward at this point.

Following discussions between London Underground and Watford Borough Council, plans outlining amendments to the design of the proposed Vicarage Road station were submitted.

The plans included new “back of house” and escape routes to the north and south of the station, revisions to cycle stand arrangements, and amendments to external lighting.

October 2017 – Crunch talks to discuss the future of MLX were arranged between Mayor of London Sadiq Khan and Watford MP Richard Harrington.

Mr Harrington said after the meeting: “There is a risk it won’t happen.”

The cost estimation has now also spiralled, with Transport for London (TfL) now quoting a delivery figure closer to £360 million instead of the previous £284m.

The project received £49million from previous Mayor of London Boris Johnson, but recent TfL cost projections show that a further £50m will be required before construction work can progress.

December 2017 - Watford Borough Council welcomed Jules Pipe, the deputy mayor of London for Planning, Regeneration and Skills, and Fiona Fletcher-Smith, director of Development Enterprise and Environment, to Watford for a “productive” meeting about MLX.

January 2018 - Richard Harrington offered the £73million shortfall needed to make the project work to start the building work, as well as control over the tracks and air space.

However, Mayor of London Sadiq Khan says "no".