The Lib Dem Mayor of Milton Keynes, Cllr Subhan Shafiq,
has resigned after personally vouching for a convicted sex offender to allow him to become a taxi driver.
Two other councillors - Lib Dem councillor Stuart Burke and Labour councillor Gladstone McKenzie - have also resigned from their posts for their part in allowing sex offenders drive taxis in the city but will remain councillors.
A number of sex offenders and people who "caused the council concern" were found to have "inexplicably" been given taxi drivers' licences during a review of taxi drivers by the council. It was subsequently found that the three had been involved in the decision to grant the licences.