It's the reality TV phenomenon built around secretive behaviour and clandestine whispers – with the sneakiest of The Traitors thriving on their ability to lie to fellow contestants. But programme chiefs have been forced to launch an internal hunt to uncover their own traitor after secrets about the show’s new celebrity spin-off series, including the star-studded line-up, began leaking out. Bosses have gone to extraordinary lengths to conceal the identities of those due to appear, with only a tiny group of very senior producers trusted with the names, and military-style security measures planned for the set. But details of those participating – including Good Morning Britain’s Kate Garraway, former England rugby star Joe Marler and singer Paloma Faith – have appeared in the media, prompting an inquiry inside the production team. Other leaked names include Stephen Fry, Olympic diver Tom Daley and journalist Robert Peston, with broadcaster Clare Balding and comic Alan Carr also reported to have been ‘approached’ by executives. A show source told The Mail on Sunday: ‘You can understand the odd detail slipping out by accident, but it has got totally out of hand this series. ‘Everyone has worked so hard to pull together an incredible line-up for the fans, and it’s a huge opportunity to do something amazing for the BBC. ‘To see that someone internally seems so intent on ruining those surprises for some reason – let’s face it probably for their own gain – is very disappointing. 'There are a lot of questions being asked now about how this can be happening when so few people are told the names in advance. ‘Obviously there will be serious consequences for somebody if they’re identified as the mole. It would probably be the biggest act of treachery in the show’s history.’ Filming for the forthcoming series, which is hosted by Claudia Winkleman begins this month at Ardross Castle in Scotland. The celebrities will all travel separately by planes, trains cars and even boat to stop their paths crossing and prevent the public from putting two and two together.