All eyes will be on Hampstead and Kilburn today, as more than 80,000 voters will have their say in mainland Britain’s tightest general election battleground.

Labour’s Tulip Siddiq, 32, a former Camden Council cabinet member, is defending retired MP Glenda Jackson’s slender 42-vote victory over the Conservatives in 2010.

Former Hampstead Rugby Club captain Simon Marcus, 42, is bidding to take the seat for the Tories. The party announced Hampstead and Kilburn as its number one target seat nationally as early as February 2013.

In 2010, the Liberal Democrats finished just 799 votes behind the Tories making the constituency a genuine three-way marginal.

But Lib Dem candidate Maajid Nawaz, 37, a counter-extremism expert and former Islamic radical, is not expected to emulate the success of 2010 due to the discontent with his party’s coalition with the Tories nationally.

The winner of today’s nail-biting contest will depend on which party, between Labour and the Conservatives, picks up the largest share of disillusioned 2010 Lib Dem voters.

Green Party candidate Dr Rebecca Johnson, 60, a nuclear disarmament expert, and Ukip hopeful Magnus Nielsen, 65, a retired tourist guide, will be aiming to pick off alienated voters on the left and right respectively.

Ms Siddiq is the bookies’ favourite to win the seat with victory odds of 1-4, while Mr Marcus is 7-2 and Mr Nawaz is 14-1.

The last survey carried out by Lord Michael Ashcroft in Hampstead and Kilburn last August put Ms Siddiq 17 per cent ahead of Mr Marcus.

But Mr Marcus predicts Labour’s proposed mansion tax will gain him an extra 2,000 votes.

Polling stations will be open from 7am to 10pm today. Votes will be counted tonight in Camden, with results expected in the early hours of Friday, May 8.

For all the latest updates on the night, visit hamhigh.co.uk.