The reason why no ones heard of quite a lot of the more recent British Films or the stars that are in them is because they hardly every get into the movie theatres and normally go straight to DVD, as a lot of movie theatres in some areas of the country can not afford to take risks on films that have not got any 'star' the general public have heard of in general they would sooner take the latest Disney, Warner Bros, Sony Pictures, etc films instead.
Some of the current guests are from a time when British Films did actually make it into the movie theatres and made money.
Also a lot of the guests are NOT people who where in masks, on Doctor Who, Star Wars, etc - they where the main stars or co-stars of the various TV and Movies they where in over the years.
ANYWAY..... a lot of the actors that where in Star Wars where British! - Alec Gunniess for one
