Joe Dempsie never knows who he will be sharing a scene with on 'Game of Thrones' until the day of filming.

The 30-year-old actor stars as Gendry, the bastard son of late king Robert Baratheon, in the hit HBO series and he revealed the show is shrouded in so much secrecy, the scripts are locked away and every character has a code name when written down.

Speaking to the i newspaper, the actor said: ''We all have secure emails now. When you get on set the call sheets, the list of scenes for the day and which characters are in them, [but] each character has a code name and unless you knew the key you wouldn't be able to figure out which character was interacting with others.

''Your pages of dialogue for the day have to be signed for in the morning and then given back at the end of the day.''

Although Joe is in one of the most popular TV series to ever hit the small screen, the actor admitted he never used his 'Game of Thrones' fame during Gendry's hiatus from the show from the end of season four until his recent return in order to further his career.

He said: ''I didn't really make the most of that opportunity at the time. I didn't hot-foot it straight over to LA and start banging on doors and auditioning endlessly.

''I stayed here and concentrated on the stuff that was being made here. I'm still in the position where I have to audition for everything I do and there have been months where work's been hard to come by.''

Joe, who shot to fame as party boy Chris in the UK TV series 'Skins', has starred in a number of British movies and TV shows, but claims he could never live in Los Angeles as it isn't a ''great recipe for sanity''.

He said: ''In between auditions or when things aren't going so well you must be surrounded by billboards for shows you didn't get.

''Sod that. It's not a great recipe for sanity.''