A cross-party candidate drawn from the Green Party, the Lib Dems and Labour could be adopted to try and break the Conservative stranglehold on the Kent seat of Canterbury and Whitstable.

The Green Party has put forward the idea of what it describes as a progressive alliance candidate to wrest away the constituency currently held by the long-standing MP Sir Julian Brazier.

He has held the seat since 1987 and the seat has been in their hands for an estimated 160 years - which according to the Guinness Book of Records is the longest uninterrupted period for a party to hold a seat.

Green Party spokesperson Henry Stanton said: "We know there are significant differences between our parties, but we also know that in every election for the last 20 years, our parties have won more votes put together than the Conservatives won.

“The majority of voters for 20 years have preferred a progressive candidate and yet we're still stuck with the same unsatisfactory and undemocratic outcome."

The 61-year-old Tory polled 22,918 votes, beating his closest challenger, Labour’s Hugh Lanning, by 9,798 votes in 2015.

Mr Stanton said the offer was serious. "We make this offer in a spirit of openness and transparency.

“We have much more in common together than any of us have with the Tories.”

In 2015, the three parties together polled 23,093 which would have given them a narrow victory over Mr Brazier by 175 votes.

It is unclear how either the Lib Dems or Labour might respond to the idea.

The Lib Dems already have a parliamentary spokesman in place James Flanagan.

Labour, which has yet to adopt a candidate, came close to winning in 2001 when Emily Thornberry - now in the shadow cabinet - came within 2,000 votes of toppling Mr Brazier.