Labour candidate Fiona Onasanya was elected to represent Peterborough at the 2017 general election, defeating Stewart Jackson, the sitting Conservative MP, by 607 votes. Following a conviction for perverting the course of justice in relation to a motoring offence in 2017 which resulted in an immediate prison sentence, Onasanya was expelled from the Labour Party in January 2019. She remained in Parliament, where she sat as an independent, and continued to protest her innocence. A recall petition in her constituency was signed by 27.6% of the electorate, more than the 10% threshold required. As a result, the seat fell vacant on 1 May. This was the second recall petition since the Recall of MPs Act 2015, and the first successful use of the procedure to remove a sitting MP. In the 2016 European Union referendum, 62.1% of voters in the Peterborough City Council area—which covers the constituency and part of North West Cambridgeshire—voted to leave the European Union. At the European Parliament election, held two weeks before the by-election, the Brexit Party was in first position in the council area, receiving 38.3% of votes.
Candidates and campaign
The list of 15 nominated candidates was announced on 9 May. Anticipating the recall petition's success, several parties announced candidates before it had even opened. Although not disqualified from seeking to regain her seat, Onasanya did not fight the by-election. Former Labour and Respect Party MP George Galloway announced his intention to stand on a pro-Brexit position and sought the Brexit Party candidacy, but was not selected. Although Galloway had mooted standing as an independent, he did not do so. The Liberal Democrat campaign focused on opposition to Brexit and calling for a second referendum. Change UK, the Liberal Democrats, the Green Party and Renew were close to supporting a joint Remain candidate, Femi Oluwole of Our Future Our Choice, but they ultimately opted to stand their own candidates, except for Change UK. Change UK's Gavin Shuker said the plan was stymied by Labour, who he said made clear that Labour would "strenuously" disrupt a joint Remain campaign. Change UK reportedly blamed Labour-aligned figures in the People's Vote campaign. Oluwole denied being pressured by Labour sources, but said he was concerned about splitting the Labour vote and allowing the Brexit Party to win. Four days before the election, Labour was urged by Jewish leaders to disown its candidate Lisa Forbes after she was reported as endorsing a Facebook post that contained an antisemitic phrase. Brexit Party candidate Mike Greene was criticised for profiteering from freehold properties and his involvement with Greybull Capital, a private investment group involved in the May 2019 collapse of British Steel. A spokesman for Greene stated that he was never an active participant in running the investment vehicle. When polls closed, the Brexit Party had been heavily favoured in bookmakers' odds to win, with Labour generally thought to be in second place.
Labour leaderJeremy Corbyn welcomed the result as an endorsement of his party's stance: "This result shows that in spite of the divisions and deadlock over Brexit, when it comes to a vote on the issues that directly affect people’s lives, Labour’s case for real change has strong support across the country". Despite the loss, Brexit Party candidate Mike Greene characterised the result as a significant breakthrough for his party, claiming to have "shaken up British politics". Party leaderNigel Farage attended the count but left before the result was announced. After the Brexit Party questioned the validity of the result, five electoral fraud allegations were investigated. It was claimed that Tariq Mahmood, who was jailed in 2008 for postal vote interference, had played a role in the Labour Party campaign for the by-election. Labour denied he had had any role in the campaign, although he did attend the count as a member of the public. The Brexit Party announced on 24 June 2019 that they would be lodging a review petition under the Representation of the People Act 1983. On 15 July, Cambridgeshire Constabulary announced the final conclusion of their investigations and determined that no offences had been committed. In 2020, Brexit Party candidate Mike Greene was ordered to pay the Labour Party's legal costs after dropping a High Court challenge. Ultimately Lisa Forbes' hold on the seat lasted for just six months. When a general election was held was held in December 2019, Paul Bristow captured the seat for the Conservatives with a majority of over 2,500 votes.
