Joining Simon and Lauren at the exclusive eatery were a host of celebrity guests including Cheryl Cole Versini-Fernandez, Amanda Holden, Alesha Dixon, Louis Walsh and of course Sinitta.
Lauren held the party two weeks before Simon’s actual birthday because he is going to be dining out at our Pride of Britain Awards on October 6.
Sir Phillip Green’s wife Tina organised the cake which had Simon and his two Yorkshire terriers Squiddly and Diddly on the X Factor judging panel.
David Walliams and his wife Lara Stone were also in attendance and the comedian left quite the impression on Simon's guests.
The Britain's Got Talent judge decided to make a speech at the bash and announced to the restaurant that he and Simon were gay lovers.
David's speech was full of innuendoes,' a source said. 'He even joked that Eric was a cover for their secret relationship.
'He said he couldn't believe the lengths Simon would go to in having a baby to cover up their relationship.'
Sinitta also opted to make a speech at the party, which must have no doubt took guests by surprise when she praised Simon's partner Lauren - despite admitting she was 'jealous' of her some months back.
'Sinitta's speech was quite serious as she talked about Simon being her best friend,' the source revealed.
'She said she is happy that she is friends with Lauren and has been for some time, adding that Lauren is now also one of her best friends. She also said how much she loves Eric.'
The celebrities partied and toasted Simon until the early hours of Monday morning while feasting Simon's favourite food spaghetti bolognase.
More photos from the event are on our PHOTO page