Cllr Sally Gimson

MP Glenda Jackson has confirmed that she will not defend the marginal Hampstead and Kilburn seat, sparking a contest to choose Labour’s next parliamentary candidate.

Cllr Tulip Siddiq is expected to throw her hat in the ring

Although the veteran MP revealed to the Ham&High in 2011 that she would contest the next general election, it was only at a meeting last Thursday that Camden Labour Party was informed of her intention to stand down.

The move has triggered speculation over who will fight for the seat, which has been targeted by both the Conservatives and Liberal Democrats.

Ms Jackson, who has been the MP for the constituency since 1992, scraped to victory in 2010 with a majority of just 42 votes – the narrowest margin in the country.

In 2011, she told the Ham&High: “If this government stays until 2015 – they may not of course, but if they do – I will be almost 80 and by then it will be time for someone else to have a turn.”

Fiona Millar could run for the seat

The Tories were due to name their parliamentary candidate last night. The Lib Dems announced last week that Emily Frith would stand for the party, in what is expected to be a hotly contested three-way battle.

Camden Labour Party has said it will consult the national party on whether to select an all-women shortlist.

Although the candidates are not expected to be unveiled until March, Highgate councillor Sally Gimson has thrown her hat into the ring.

Cllr Gimson, who unsuccessfully stood for the parliamentary seat of South Leicestershire in 2010, said: “I am interested in standing, but obviously this is at the very beginning of a very long selection process.”

Camden Council cabinet member Cllr Tulip Siddiq has not publicly declared her intention to seek the candidacy, but is understood to be interested in standing.

Fiona Millar, an education writer and the partner of former Labour spin doctor Alastair Campbell, has also been mooted as a possible candidate, but party insiders said they doubted she would contest a full-on selection battle.

Camden Council leader Cllr Sarah Hayward has ruled herself out and said she would remain impartial.

Sources within the Labour Party said they were keen for a familiar face in the community to replace Ms Jackson, who lives in Blackheath, south London.