Mark Hamill Luke Skywalker Star Wars
Mark Hamill as Luke on location on the Skellig Islands off Ireland. LucasFilm

Since the release of the first trailer for Star Wars: The Last Jedi, fans have been debating what exactly is going on with Luke Skywalker, the hero of the Rebellion who brought down the Empire but has spent the last 20 years in exile.

In the trailer, Mark Hamill's iconic character utters the words: "It's time for the Jedi to end." The line suggests a darker, broodier take on the character and his look backs this up – but is this Luke still the heroic figure audiences once knew him as?

We'll find out in December, but in a new interview Hamill has revealed one of his ideas for The Last Jedi involved this Luke literally not being the same character we once knew. Instead, he would be an evil twin.

"Oh baby, would I love to play my own evil twin!" Hamill told Empire Magazine. "It'd be great because you could maybe not reveal it's Evil Luke until the real Luke shows up.

"We could watch this guy undermining the good guys secretly, maybe even killing a supporting character out of everyone's sight so they all go, 'What's going on? He's crazy!' And then, of course, the good Luke shows up."

To be clear, this isn't what happens in The Last Jedi – and there's a good reason for that.

"When I suggested that storyline, they said, 'Well, it's been done.' Apparently in one of the Star Wars novels they clone an evil Luke from the hand that got cut off. Over the years there have been so many permutations of these characters that there's not much left. It's really limiting!"

Hamill's is referring to Timothy Zahn's 1993 Star Wars novel The Last Command, in which the clone, called Luuke Skywalker (not a typo), eventually battled the real Luke before being taken out by Luke's wife Mara Jade.

The book was part of the old Star Wars expanded universe, which was retconned out of the official, canonical story when Disney bought LucasFilm and announced a new series of sequels.

By Hamill's own admission the evil Luke storyline is pretty bad, calling himself a "fountain of really terrible ideas".

The 65-year-old actor was eager to talk about the ruled out ideas, but when it comes to what the film actually has in store for Luke he was a lot more cagey, eager to keep the film's secrets in the final stretch before its release.

"He's changed a lot," he says. "It was as shocking for me to read what Rian [Johnson, director] had written as I'm sure it will be for the audience. I was surprised by the way he saw Luke - to hear him say something like, 'It's time for the Jedi to end' - and I wasn't even sure I agreed with it.

"Being the caretaker of the character I have a possessive attitude towards him, but even though it's not the way I would have gone, the more I got into the work, the more I realised I was wrong."

Luke Skywalker was seen at the very end of 2015's The Force Awakens, when new hero Rey (Daisy Ridley) hands him his old lightsaber. In The Last Jedi, Luke reluctantly teaches Rey the ways of the force, but his attitude has clearly changed over his years in self-imposed exile.

Star Wars: The Last Jedi will be released in the UK on 14 December.