In addition to a sizzle reel, which was live-streamed and later released online, a second trailer — featuring Darth Vader — was revealed to the audience. But those not lucky enough to be in attendance did not get to see the trailer.

"I'm probably a lot like everyone in this audience," said Edwards to the several thousands in the crowd. "I watched A New Hope every day until my Betamax had worn out."

Although the director said that the entire shoot had been the "most insane, surreal experience," one tipping point came when Mark Hamill visited the set.

"He was wearing a Godzilla T-shirt," laughed Edwards, whose previous film was Godzilla. "I don't know what I said to him. I was trying to be articulate, but all I could really think was, 'Please Lord, someone be taking a photo of this.' "

Another special guest came in the form of George Lucas, who popped by one Monday.

"I was told on Friday and spent the whole weekend crapping myself," Edwards said. "I challenge anyone to have a more surreal experience than showing a Star Wars film to George Lucas. He'd criticize things, but then we'd realize he was joking. But we'd all be having heart attacks."

The Death Star rises in this new poster for #RogueOne: A Star Wars Story. Just revealed at #SWCE! pic.twitter.com/aopNW6DzXq — Star Wars (@starwars) July 15, 2016

Felicity Jones (Jyn Erso) and Diego Luna (Cassian Andor) talked about their key rebel characters.

"I feel there's one major difference between Jyn and other Star Wars heroes, like Rey and Luke, and that main difference is that she isn't a character asking, 'Who am I and where have I come from?'" said Jones. "We know that about her. And that fact propels the story and is the beginning of Jyn's journey to find out what her reason is and her cause."

Luna said that Cassian, who works in intelligence for the Rebellion, and Jyn start out as a twosome, but the team grows.

"And like any team, there are frictions, there are issues and it's Cassian who has to keep them together."

One of the central members of the team is a reprogrammed Imperial droid called K2S0, played by Alan Tudyk. As footage of the droid shot in Jordan was shown, Tudyk discussed his robotic character. "He's 7-foot-1, and black, which is really my inner person," he joked. "He's not quite all there; he speaks his mind and says things that could be unsettling … just very honest. If you know any old people, it's like that!"

Tudyk also revealed that he had a chance to meet Anthony Daniels — who plays C-3PO — at the Force Awakens party. "I told him I'm going to be the next droid, and he said, 'Do you wear a suit or are you CGI?' so I said 'I'm CGI' and he said, 'You shit!'"

Riz Ahmed, fresh from the Jason Bourne premiere in London earlier in the week and the success of The Night Of on HBO, discussed his pilot character, Bodhi Rook, acknowledging his less celebrated Imperial past. "He does work for the Empire to earn a living," he said. "People work at big organizations and don’t agree with everything they do. You don’t have to get judgy!"

However he said that the actions of the Empire, especially on his home planet, which is occupied, force him to question what he's doing.

Mads Mikkelsen got arguably the biggest applause when introduced, but gave away the fewest details about his character, Galen Erso, Jyn's father. "It would be a big spoiler to say too much … he's a person of interest, a scientist," he said. "At one point he invented something so beautiful, so fantastic, that it might change the universe."

Some of the Rogue One shoot took place in the Maldives, a "paradise" location that Edwards said he "took one for the team" to shoot in. It's here that Forest Whitaker's Clone Wars veteran Saw Gerrera is introduced. "He's a guerrilla fighter controlling a rebel group. These groups all come together as an alliance," Whitaker said, adding that Gerrera was also trained by the Jedi.

Having first entered the conference hall in full white flowing Empire robes, Ben Mendelsohn quickly changed backstage to discuss his Imperial military director Orson Krennic. "He's a very different villain. He's an Australian kind, we do villainy very well," he joked. "But he's smarter than most of his predecessors. He's perhaps a little sexier than some of them too."

The panel discussion took place in London's Excel Center, just four stops on the London Underground from where Edwards revealed he did some secretive, late-night Rogue One shooting. "I used to work in television and pass the Docklands Light Railway every day," he said. "It looks like something from the future, and I thought, 'If I ever get to do a sci-fi film, I'm going to film it here.'"

Edwards parked that thought, but years later managed to fulfill his ambitions with a secret mission: "We went down and as soon as it closed at midnight, you saw these guys in suits getting the last train. As soon as they'd gone, we all dived in, we had four hours and had to set-dress the whole thing, bring all the stuff in and we shot the scenes and had to be out by 4 a.m. We're just getting the last one in and as we left all these guys in suits came back in and we're like, 'Morning, morning.' I so desperately wanted to tell them, 'We just shot Star Wars!'"

Star Wars Celebration Europe continues through Sunday.