Dispatches and Channel 4 News will broadcast CCTV footage tonight they say sheds "new light" on the confrontation between Andrew Mitchell and Downing Street police officers which became known as "Plebgate".
They claim the footage shows an exchange that "raises questions about the description in police logs leaked to the media".
Britain's most senior police officer has promised a "ruthless" investigation into an alleged conspiracy against Andrew Mitchell.
Andrew Mitchell has written a piece in which he has accused the police of trying to destroy his career in a smear campaign.
Police investigating the row involving Andrew Mitchell have arrested a second man today. See how the "plebgate" events unfolded.