Labour could face another by-election test in the coming weeks if reports that Boris Johnson is planning to quit the Commons are confirmed.
The Times and Telegraph newspapers claim Conservative strategists are considering a quick exit for Mr Johnson, who beat incumbent Ken Livingstone in the London mayoral election earlier this month.
According to the Times a by-election could take place as soon as June 26th or July 3rd.
Such a move could see the replacement for Mr Johnson increase the Tory majority in traditional Conservative heartlands, further increasing the party's momentum after it overturned Labour's hold over Crewe and Nantwich in yesterday's by-election.
The Henley Tories advanced to a majority of 12,793 in the 2005 election, with the Liberal Democrats' Stephen Kearney in second on 12,101 votes.
Tory strategists are concerned the Lib Dems, usually a strong fighting force when it comes to by-elections in which they have a competitive chance, may make progress if they are given time to build a strong campaign.
The news comes one day after Mr Johnson announced the appointment of businessman Tim Parker as first deputy mayor.
Mr Parker, renowned for his tough-talking record with firms like the AA, Kwik-Fit and Kenwood, will be a key part of Mr Johnson's pledge to deliver "value for money" for the capital.