By politics.co.uk staff
A 23-year-old man has been arrested over the 'plebgate' affair involving Andrew Mitchell.
The arrest comes amid a growing concern in Downing Street at the actions of police involved at the scene.
The man was been taken into custody in relation to "intentionally encouraging or assisting the commission of an indictable offence".
Scotland Yard said the man is "not a police officer or a member of police staff".
Thirty officers have now been put on the case.