Princes William and Harry inspect  Star Wars troops in London premiere

The princes tried not to overshadow the impressive cast of Star Wars: The Last Jedi at Tuesday night's premiere - but fans are already talking about their cameo.

The secret part of Prince William and Harry could have already been narrowed down to a short sequence in the Star Wars: Last Jedi film, thanks to their towering height, the Daily Mail reports. 

Breezing past a line-up of Stormtroopers - who are required to be 5ft 11in in height - on the red carpet, the duo certainly seemed a little tall to play the imperial troopers.

While it's nigh-on impossible to identify the duo in the new film, thanks to their white helmets and full shiny suits, speculation about their role has reached fever-pitch including reports that their height has blown the secret.

Fans of the franchise may know that Stormtroopers have to be 5ft 11in to play the part of the men in white suits.

However, Prince William is a towering 6ft 2in and Harry is only a fraction less at 6ft1in, which could set them apart from the rest of the group.

According to a report in The Telegraph, the towering princes feature within a group of Stormtroopers guarding the Empire ship in the 152-minute film, as speculation mounts about their Hollywood cameo.

The duo are said to be part of a group who reprimand rebels Finn - played by John Boyega - and DJ - played by Benicio Del Toro. 

Harry and William were pictured at Pinewood Studios last April, when their secret film cameo was unveiled to the public.

A source told The Mail on Sunday at the time: ‘The line given was that they were going to have lunch and a private tour of the rest of the set.