By Giles Kenningham In this column, former No 10 advisor Giles Kenningham analyses the worst comms screw-ups of the election campaign. So what took the prize for the worst PR gaffe this week? What is it with politicians and food? Ed Miliband eating that infamous bacon sandwich. Peter Mandelson getting covered in custard at a carbon summit in 2009. And of course egging. Pelting politicians with eggs is a long-standing tradition that dates back more than 50 years when the then Labour Prime Minister Harold Wilson was hit with one by a frustrated Tory voter. When I worked for David Cameron we carr…