Dust-up at Downing Street becomes crisis for Britain's top police force

FILE - In this May 17, 2011 file photo, Andrew Mitchell arrives at Downing Street, London. Mitchell, who resigned from a government post over allegations that he used derogatory remarks against police officers called on Tuesday, Dec. 18, 2012 for a full inquiry into the dispute amid new claims that police fabricated the evidence. Mitchell quit as the government's chief whip in September after he was accused of swearing at police officers who stopped him from wheeling his bicycle through the Downing Street gates. (AP Photo/PA, Yui Mok, File) UNITED KINGDOM OUT, NO SALES, NO ARCHIVE (The Associated Press)

It started three months ago with an angry exchange over a bicycle in front of the British prime minister's official residence. Now, the controversy over what a senior politician did or didn't say to officers guarding Downing Street has grown into a full-blown crisis, raising new questions about police ethics.

Writing in The Sunday Times, Andrew Mitchell said he was the victim of a conspiracy, saying that a report which quoted him as describing police as "plebs" — an insulting term for a working-class person — had been faked.

Mitchell resigned as the Conservatives' chief whip in October as the scandal rumbled on, but the arrest of two police officers allegedly involved in lying about the incident has revived his political fortunes — and raised new questions for Scotland Yard.