Officers also previously interviewed a woman in her 30s under caution in connection with the same investigation. The spokesperson added: “The investigation continues.”
Scotland Yard did not name any political party in its statement, and the spokesperson did not confirm which political party its investigation related to.
However, three other people with knowledge of the circumstances, all of whom were granted anonymity to discuss an ongoing case, said the investigation relates to a long-running dispute connected to the establishment of Your Party.
The left-wing party was co-founded in summer 2025 by the former Labour Leader Jeremy Corbyn and the former Labour MP Zarah Sultana, both of whom now sit as Your Party MPs in the House of Commons.
The two MPs clashed publicly over a September 2025 email that was sent to around 800,000 people on the new party’s mailing list, encouraging them to sign up as paying members. Sultana had promoted the membership portal while Corbyn described its launch as “unauthorised.” Sultana later said her sole aim had been to “safeguard the grassroots involvement that is essential to building this party.”
Neither the man arrested, nor the woman interviewed by police, are MPs and neither have been charged with an offence. Neither Corbyn nor Sultana are accused of wrongdoing.