Sir Elton John will bring on four special guests during his headline show at Glastonbury this weekend, his husband David Furnish has revealed.The Rocket Man superstar will take to the Pyramid stage at Worthy Farm on Sunday night for what has been billed as his final UK gig. Discussing Sir Elton’s plans for surprises at the show, David told Sky News’ Beth Rigby: “Four collaborators of his choosing. People, he just thought, ‘I’d really like to do something with these artists at Glastonbury’.