By Tim Masters
Entertainment editor, BBC News website
Visitors might bump into a few familiar characters
Dusk was closing in. A group of storm troopers took up defensive positions along a stretch of red carpet.
And then out of the darkness emerged Darth Vader - more than two metres tall - causing the assembled crowd to shrink back in fear.
It sounds like the opening scene of a Star Wars movie - a long time ago in a galaxy far, far away.
But this was a Friday night on the south bank of the Thames in London, a lightsaber's throw from the London Eye.
It was the kind of lavish launch party you would expect from a multi-billion dollar franchise.
Lots of theatricals, a smattering of celebrities and some actors from the movies.
Star Wars: The Exhibition has come to London to mark the 30th anniversary of the first film's release.
The film opened in just 32 cinemas in the United States on 25 May 1977.
It went on to become a global smash with children across the world re-enacting the adventures of Luke Skywalker, Princess Leia, Han Solo and Obi-Wan Kenobi.
Many of those at the launch were children of the '70s - now well into their 30s and 40s.
But they still queued up like excited infants to be photographed with Darth Vader.
Another guest much in demand was Anthony Daniels, the actor inside the fussy, shiny droid C-3P0. He worked on all six Star Wars films.
"It's great to see some of my old friends, costumes and exhibits - including my own costume which is safely in a glass box so I can't put it on!" he told BBC News.
Daniels is clearly proud to be part of the Star Wars universe, and to see it brought together in one place.
"It's a reminder of the huge thing that Star Wars has become over the last 30 years," he said.
"It's also extraordinary to see an audience come though here of any age, smiling at the objects, and it's magic to be a part of that."
So what will visitors to the exhibition actually see?
The items have been brought from the LucasFilm Archives in California.
They include a full-size Naboo N-1 starfighter along with Anakin's Podracer from Episode I: The Phantom Menace.
There are many rooms to explore, themed by planet: Tatooine, Endor, Hoth and Geonosis to name but a few.
Many of the original costumes can be seen close up
And let's not forget the Death Star. No prizes for guessing who takes star billing there.
It's a slightly odd experience to find such futuristic artefacts on display along the wood-panelled corridors of County Hall.
Visitors should be prepared for encounters with Jedi Knights and Sith Lords.
There is also a training school for people keen to hone their lightsaber skills.
I took along my seven-year-old son to get a younger perspective.
He was rendered speechless with delight at coming face to face with the likes of Yoda and R2-D2, and scared witless at Darth Vader's attempts to recruit him to the Dark Side.
But it was the class of '77 who were gurgling the loudest with delight - somewhat in the manner of Jabba the Hutt - as their bemused partners and offspring looked on.
Star Wars: The Exhibition is open now at County Hall, Westminster, London.