(well, I had to go with the gorging style food option)
from the Sunday Times article:

I thought, of course, I was being clever, and no one would ever know, but Pauline realised in the end. The signs in the toilet gave it away

Which rather explains why:

Taxpayers also paid more than £3,000 to clean the apartment, which was previously occupied by John Prescott.

if he couldn't even be bothered to clean the loo up properly after he'd yacked.