David Cameron today made a surprise campaign visit to Margaret Thatcher's former constituency amid growing Tory fears of a Labour victory.
Recent opinion polls show Labour within striking distance of capturing the trophy seat of Finchley & Golders Green.
Conservative Mike Freer, who won back the seat from Labour in 2010 is defending a majority of 5,809.
Finchley and Golders Green is on Labour's list of 12 target seats in London but it was not regarded by the Tories as a 'key marginal'.
However, a YouGov opinion poll for the Evening Standard three days ago showed Labour 12 points ahead of the Conservatives in London - a large enough lead to make Finchley vulnerable.
The Prime Minister's visit to Archer Academy, a new free school in East Finchley, was being seen as a sign of Tory nerves.
The Prime Minister chatted to pupils and gave interviews to eight local newspapers and websites.