NAOMI CAMPBELL is pulling out all the stops to ensure her "adopted granddad", Nelson Mandela, has a 90th birthday to remember. Campbell is said to be helping organise festivities for a blow-out summer event, where the likes of Bono, Rihanna, Jay-Z and Leona Lewis will perform. Friends such as Kate Moss and Lewis Hamilton are also rumoured to attend. And as if a supermodel party planner and the most stellar guest-list on the planet weren't fabulous enough, the grapevine is buzzing with whispers that Robbie Williams will perform at the event with Queen - dressed as the band's legendary front man, Freddie Mercury. (April 30 2008, AM) Leisa Barnett