Boris Johnson agrees to be blasted by water cannon

London Mayor Boris Johnson has said he is prepared to be blasted by water cannon after he authorised the Metropolitan Police to buy three of the devices.

Speaking at City Hall, he said he was volunteering to undergo the experience to reassure Londoners they were safe.

The cannon have not yet been bought but a Number 10 spokesman said David Cameron believed the police should have the resources they wanted.

Number 10 added there was still "a process of licensing and regulation to be completed and a final decision will be taken by the home secretary".

Public order expert Clifford Stott told BBC Breakfast deploying water cannon was not always an effective way to calm a hostile situation.