LONDON (AFP) -- A protester threw a cupful of green custard in the face of business secretary Peter Mandelson on Friday, in a stunt to highlight opposition to a new runway at London's Heathrow airport. Mandelson was arriving for a London summit on carbon strategy when protester Leila Deen approached him and hurled a large cupful of custard straight in the former European Union trade commissioner's face, at close range.