Guardian: Mandelson reacts after the protest Link to this video Lord Mandelson was hit in the face with a cup of green slime by an anti-airport protester as he arrived to attend a low-carbon energy summit in central London this morning. News cameras showed the minister genially approaching a young woman after he got out of his car and receiving a large proportion of the emerald green liquid – later identified as custard containing added colouring – that she threw at him from a cup …