Holly Willoughby, Alison Hammond and Dermot O'Leary have led the celebrity tributes to Davina McCall after she revealed she's undergoing brain surgery to remove a benign tumour. The TV presenter, 57, shared the news in an Instagram post, saying she has a 'very rare' colloid cyst that affects only three in a million people.  She explained that she received the diagnosis by chance after booking in for a 'health scan'.  ...