Police officer and woman arrested in 'plebgate' probe
15 June 2013 Last updated at 16:13 BST
Two more people, including a serving UK police officer have been arrested over the "plebgate" row involving the former government chief whip Andrew Mitchell.
The male constable, aged 48, was arrested on suspicion of misconduct in a public office on Saturday morning.
A 49-year-old woman was also arrested on suspicion of assisting an offender.
The MP has apologised for not treating officers with respect after he was told not to take his bike through the main Downing Street entrance in September.
Sarah Campbell reports.