The passionate pair were so overcome by lust they FORGOT they could be seen through the window of the brightly-lit eaterie.
One Manchester reveller told how he and his mates had earlier spotted the pair snogging.
The witness grinned: “We just assumed it was a couple of the staff who’d got carried away.
“We popped into a club, then later walked past the same restaurant. Things had hotted up.
“The fella had his trousers round his ankles. Everyone was gobsmacked.
“The whole place was brightly lit and we had a great view. There was an empty bottle of wine and two glasses on a table.”
A shocked Pizza Express spokesman said: “We are obviously taking this seriously and looking into the matter immediately.” ( thesun.co.uk )