Oscar winner Dame Helen Mirren

Dame Helen Mirren has been partying with P. Diddy in Las Vegas.The 61-year-old actress - who won an Oscar for her role as Britain's Queen Elizabeth II - was in the city to attend the grand opening of the exclusive new club Tao Beach last week. A source told E Online: "She arrived with her husband Taylor Hackford, looking very out of place in her prim and proper white eyelet dress and cotton cardigan."But she shocked everyone when she heartily welcomed Sean 'Diddy' Combs with a gracious hug."Tao restaurants in Las Vegas and New York have always been top celebrity hangouts. The new Beach venue, located at Vegas' Venetian Hotel, has a VIP poolside lounge. Sacha Baron Cohen, Will Ferrell, former Heavyweight Champion of the World Lennox Lewis and Ashanti were also in town for the launch party. But there was no sign of Dame Helen at the end of the night when Diddy, Jay-Z, 50 Cent, Usher and Nelly were partying hard in the VIP room A source said: "The boys passed gold-plated bottles of Jay-Z's Ace of Spades champagne back and forth and were singing along to their own songs."Then Diddy got on the mike to tell everyone how lucky they are to be in the same room as the 'most powerful black man ever.' "