Leonardo DiCaprio has joined the four-day festivities for British billionaire Sir Philip Green’s 60th birthday in Mexico. The actor is partying away with other stars, including Kate Moss and Simon Cowell, at the lavish bash at a luxury resort in the Riviera Maya. Topshop and Arcadia boss Sir Phil has flown in more than 100 friends by private jet from London and Miami for the birthday bacchanal, rumored to cost $25 million. The bash, masterminded by Sir Phil’s wife, Tina, will also include a party for their daughter Chloe’s 21st birthday, with performers including Rihanna and Bruno Mars. We’re told guests are also being issued Spanish-themed costumes to wear on one of the big nights.