The mayor of Watford said the Met Line extension is too important to be held up by “political wrangling”.

But Mayor Dorothy Thornhill, who took three days to reply to the Observer, failed to address what £10 million of taxpayers’ money had been spent on.

READ MORE: Metropolitan Line Extension - everything you need to know

Earlier this week, a Freedom of Information request revealed that £130 million of Hertfordshire taxpayers' money had been used to fund the project - £10 million came from Watford Borough Council.

She said she will continue to work with local businesses, Hertfordshire County Council, Herts LEP and MP Richard Harrington to lobby the transport minister Chris Grayling and mayor of London Sadiq Khan.

She said: “The Metropolitan Line Extension will deliver significant economic growth, not just in Watford, but across north west London and south Hertfordshire.

“It underpins important regeneration schemes in the town and we know that local, national and international businesses see this new infrastructure as critical to their business planning and ongoing success.

“Our projections show the benefits of the extensions to the Watford and wider economy, including London, will run into many millions over the years and the predicted shortfall should be seen as part of the bigger picture in delivering much needed improvements to this country’s vital infrastructure.

“With design work due to be completed in July, TfL and the Department for Transport must come to a funding arrangement as soon as possible to allow the next phase of the project to commence without delay.”