According to the BBC, 'senior Downing Street source told the BBC that Mr Mitchell was in a "much stronger position" following the latest developments in the plebgate story' http://www.bbc.co.uk/news/uk-politics-20795489 but this report also tells us that there was "no reason to doubt the accounts of officers directly involved in the incident".
Let's guess that Andrew Mitchell actually said "plod", and the policeman misheard. Mr Mitchell would have been glad of that because it allowed him to say, correctly, that he had never used the word "pleb", while diverting attention away from the true issue which was his swearing and his denigration of a police officer just doing his job. The media, in turn. would have been happy to run with that because they could hardly call it f*'%#£&gate.