Cowell had no idea that festivities for Jackie's birthday were going to be extended to him when he turned up at the party in West London. Jackie had organised a dazzling performance featuring some of the music mogul's closest buddies.
Dannii Minogue, Amanda Holden, American Idol judge Randy Jackson and Louis Walsh sang the Carly Simon chart-topper You're So Vain. They were planning to give Simon the performance of his life. "Jackie went to extraordinary lengths to organise the bash for Simon. She even told the guys performing they were singing for her - but it turned out they were there for Simon," the Mirror quoted a source as saying.
"She knew the performance would really make him laugh. Dannii took the lead vocals and the others came out providing the comedy for the show. Jackie knew Simon would find it hysterically funny - especially when Louis joined in the singing. Simon is so vain but, unlike some, he is the first to admit it. So it was the perfect joke," the source added.