They want you to buy their festive single, 'Christmas Time (Don't Let The Bells End'). Chances are you already have. If not (like, duh), pop along, buy the single, and have 'em scribble all over it whilst you're there. It'll be worth something in the future! Like, £4.99 or something. If you're lucky.
The signing session begins at 9.30 and will run for an hour. Be there or be at work like most regular folk are at 9.30 on a Friday morning. Or stuck in a tube tunnel somewhere under Covent Garden, as I am most Fridays.