Deputy leader of Reform UK Richard Tice speaks to BBC London ahead of the party's conference.
Sheffield and Barnsley councils have seen several resignations since local elections in May.
A 25-year-old man has been arrested on suspicion of conspiracy to defraud, police said.
Craig Wiles resigns from Kirklees Council just a matter of weeks after the local election.
Voters tell the BBC they have switched to Reform after becoming disillusioned with Labour.
Rachel Sunderland, Alun Griffiths and Aislin Naylor are elected in Idle and Thackley.
Three seats in the Idle and Thackley ward were not contested in May after a candidate died.
Reform UK's election campaign raised the prospect of Havering leaving Greater London - a position their local leader now disowns.
Several newly elected councillors have been suspended over their historical social media posts.
