By Danny Shaw
Home affairs correspondent, BBC News
Since Sir Ian Blair's sombre statement announcing his resignation as Metropolitan Police Commissioner on Thursday, there has been a sense of shock that the UK's most senior policeman could have been removed so swiftly.
Sir Ian Blair is not the first police chief to step down under political pressure
Home Secretary Jacqui Smith and Ken Livingstone, London's former mayor, were among those to criticise the role of current Mayor, Boris Johnson, in Sir Ian's departure.
Indeed, it is the first time that a directly-elected mayor has forced out a British police chief.
But it is not the first time that politics, or politicians, have played a part.
David Blunkett, Labour's home secretary from 2001 to 2004, called for - and achieved - the removal of Sussex Chief Constable Paul Whitehouse in June 2001, over the police shooting of an unarmed, naked man, James Ashley.
Three years later, Mr Blunkett demanded the removal of Humberside Chief Constable David Westwood after his force was criticised in a report into failures in police intelligence in the case of Soham murderer Ian Huntley.
A bitter and very public tussle followed, between Mr Blunkett, Mr Westwood and Humberside's police authority, resulting in a compromise whereby the police chief retired a year early.
David Blunkett's role in the second case followed a law change, in the Police Reform Act 2002, which gave the home secretary the right to intervene in forces he considered to be failing.
In many ways, Boris Johnson's decision to request the resignation of Sir Ian Blair, can be seen as a continuation of that process - under which politicians have more say in who runs the police.
And it is likely to gather further momentum with both the government and the Conservatives, if elected at the next election, planning to extend the role of directly-elected officials in policing.
In its green paper on policing, the government proposes that in future the public will directly vote for the majority of police authority members. They will be termed crime and policing representatives.
The Tories are calling for directly-elected police commissioners to replace police authorities and hold chief constables to account.
The departure of Sir Ian Blair, it seems, is simply a taste of what is to come.