Fiona Onasanya Independent Lisa Forbes Labour A 2019 by-election took place in the Parliamentary constituency of Peterborough on 6 June 2019.

[2] The seat was vacant following the removal of the former Labour MP Fiona Onasanya by means of a recall petition triggered by her conviction for perverting the course of justice.

[8] Owing to the jury at the Old Bailey failing to reach a verdict, Judge Nicholas Hilliard QC ordered a retrial.

[8] At the retrial, Onasanya was found guilty and compared herself afterwards to several biblical figures including Moses and Jesus who had been convicted by courts in their day; she declared her intention to appeal.

The court officially informed the Speaker of the House of Commons who, later that day, took the necessary steps to initiate the process which included notifying the petition officer for the constituency.

[21] The threshold for success was 10% of eligible constituents (6,967 out of 69,673) signing within the six-week period (ending 1 May[note 1]) in order to recall Onasanya and call a by-election.

[24] No ongoing tally was reported by the petitions officer, thus it was not known that the required threshold had been reached until the end of the six-week period.

[25] There was no opinion polling, as UK law prohibits forecasts of the outcome of recall petitions which are based on statements from, or surveys of, potential signatories.

This represented 27.64% of the 69,673 electors eligible to sign the petition, thus surpassing the 10% threshold, causing the seat to become vacant, and triggering the 2019 Peterborough by-election.

[49] 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.

[51] 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 leader Jeremy 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".

[57] 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.