Business Secretary Lord Mandelson has had green custard thrown over him by a protester as he arrived at the launch of a low-carbon summit in London.
The protester, Leila Deen, is a member of the Plane Stupid group campaigning against a third runway at Heathrow.
The move was a "last resort" after the democratic process failed, she said.
Lord Mandelson said security was a police matter but he did not want to "go back" to the 24-hour protection he had when Northern Ireland Secretary.
The business secretary said people should not "over-react" to the incident.
He stressed he had chosen not to continue with "round the clock" protection - which he is entitled to as a former Northern Ireland secretary - and he hoped this would not now be necessary but security issues were a matter for the police. More custard here... http://www.planestupid.com/