What does history tell us about the success of those who challenge election results?
Since 1923 only three mainland election results have been overturned by the court. The most recent was the Oldham East and Saddleworth result from the 2010 general election. The defeated Liberal candidate, Elwyn Watkins, launched a challenge to the election of the Labour candidate Phil Woolas. The election result was declared void and Woolas was barred from standing again for three years. However, the resulting by-election was won by the replacement Labour candidate, Debbie Abrahams – a court victory, but not an election victory for the challenger.
In the 1997 general election the Liberal Democrat candidate, Mark Oaten, was declared the winner by a margin of two votes. Gerry Malone, the defeated Conservative challenger successfully applied to have the election declared void. However, in the resulting by-election Oaten beat Malone by the somewhat increased majority of 21,556 – a resounding reaffirmation of the election result and an end to the political career of the challenger.
In 1960 Labour MP for Bristol South East, Tony Benn inherited a peerage, when his father, Viscount Stansgate (formerly William Wedgwood Benn) died. In those days a peerage debarred the holder from sitting in the Commons and Benn was forced to leave, even though he did not wish to go to the House of Lords. Tony Benn tried unsuccessfully to rid himself of the unwanted peerage, but at that time there was no mechanism for doing so. A by-election was called. Tony Benn stood again in the by-election and received the most votes. However, his defeated Conservative challenger, Malcolm St Clair, had the result overthrown by the court and was declared the winner, even though he had been closer to losing his deposit than to winning a majority. Tony Benn then embarked on a campaign to have the law changed. In May 1963 the Peerage Act was passed, paving the way for hereditary peers to renounce their titles and their seats in the House of Lords and enabling them to contest seats in the Commons. Tony Benn became the first peer to renounce his title under the Peerage Act, when it became law. Malcolm St Clair resigned the Bristol seat, precipitating another by-election, which Tony Benn won – a temporary victory for St Clair, the challenger in this case, as he held the seat from 1961 to 1963.
These examples suggest that challengers don't tend to reap much electoral benefit.