The chief constable of West Mercia Police has apologised for the findings of an investigation that initially found three Police Federation officers who met Andrew Mitchell had no case to answer for misconduct.
Chief Constable David Shaw has overturned the earlier finding and written a personal letter of apology to the former Chief Whip.
He has asked for another chief constable to be called in to review the decision not to take action against the three officers.
He told the Home Affairs select committee: "Clearly the buck stops with me and I have to be accountable for a huge range of things that go on.
"It's unedifying and it hurts the force."