Media playback is unsupported on your device Media caption The Star Trek captains - (l to r) Scott Bakula, Avery Brooks, Kate Mulgrew, Sir Patrick Stewart and William Shatner. Photo by Theo Cohen

The UK's first official Star Trek convention for more than a decade has brought together all five captains from across the TV show's 50-year history. BBC News was there to witness the occasion.

A Star Trek convention is pretty much like its stereotype. Fans dress up as their favourite character - alien or human - and queue up for hours for the opportunity to have their photo taken with one of the sci-fi show's stars.

Yet some unique things have happened at Destination Star Trek, which runs at London's Excel Centre until Sunday.

It has hosted the UK's first Klingon wedding - the bride and groom were Swedish - and broken the Guinness World Record for the largest gathering of fans dressed as Star Trek characters.

It has also managed to bring together all five starship captains - Kirk, Picard, Janeway, Sisko and Archer - for the first time outside the US, and for only the second time ever.

Media playback is unsupported on your device Media caption William Shatner: "I did a documentary called The Captains and I learnt to love every one of them"

For Trek fans this is a big deal. Indeed, it is rarer than having five US presidents in the same place at the same time.

"I would presume getting together is a problem because we live in divergent areas of the world," William Shatner, who kicked it all off as Captain James T Kirk, tells the BBC.

The 81-year-old assures us that any friendly rivalry between the five "has long since passed" and they are now "good friends".

The event was looking doubtful when Sir Patrick Stewart - aka Jean-Luc Picard - was absent for the group's press photocall to promote the occasion.

But he did materialise on stage later for their question and answer session, which hundreds of people had paid £95 each for the privilege of attending.

Fans were given the opportunity to speak directly to their heroes and hear them reminisce about their days in the captain's chair.

Captain's chair

Hosted by John Barrowman - no stranger to the sci-fi convention circuit himself thanks to his involvement with Doctor Who and Torchwood - this was very much a light-hearted event.

The captains were asked if they believed in alien life (they all do), the titles of their favourite books and what would they be doing if they were not actors.

If they could add anything to their captain's chair, what would it be? "A Twitter account," Sir Patrick quips, while Shatner suggests "a toilet".

Most embarrassing fan moment? "The lady that brought out her left breast to be signed," says Shatner, who happily obliged.

Scott Bakula (aka Jonathan Archer) admits he has yet to experience an embarrassing fan. So Barrowman leaps across the stage and pulls down his jeans so the former Quantum Leap star can sign his right buttock.

Image caption Fans attended the event dressed as their favourite Trek characters

One fan even asks the captains to sing Happy Birthday to help him celebrate his special day. It results in a particularly rousing rendition from Sir Patrick, Shatner and Kate Mulgrew (aka Kathryn Janeway from Star Trek: Voyager).

The atmosphere is a cross between a concert, a political rally and an evangelical gathering.

Every response to a question is met with wild cheering and clapping - even when Mulgrew says she would have been be a doctor had she chosen a different career path.

The same sentiment could be seen elsewhere in the convention. With VIP tickets sold out at £3,000 each, some people had deep pockets to spend time with the stars.

'Part of society'

Stalls selling Star Trek merchandise were dotted around the venue, and sci-fi shop Forbidden Planet also had a presence.

Jon Harrison, the store's internet and marketing manager, says selling at conventions can be lucrative.

"It depends on the show," he says. "Sometimes they can be really hot and sometimes not so exciting, but this one looks like it will do well."

Top sellers, he says, include busts of Kirk and Picard that sell for £59.99 each, and a new book offering a guide to the Klingons' Bird of Prey ship.

For fans Hannah Southworth, 24, and Steve Cope, 29, it is their first Star Trek convention. They estimate they have spent about £100 on their first of three days at the event.

Image caption Only four of the Star Trek captains attended the official press photocall

The pair travelled from Bath sporting their Starfleet uniforms after hearing all five captains would be making an appearance.

"The main reason I'm here is for Patrick Stewart - I think he's amazing," says Steve.

"I'm a big fan of the show and had grown up watching it," Hannah adds. "It's been around so long it's a part of society now."

Both rate themselves as a 10 on the scale of fandom, though Hannah says it "depends on how you express your fanaticism".

Back on stage, the captains are asked what one thing they would change about their series.

"To be renewed for another three years," joke Shatner and Bakula. Both their shows - the original Star Trek and prequel spin-off Enterprise - were cancelled after their third and fourth seasons respectively.

But it is Avery Brooks (aka Benjamin Sisko from Star Trek: Deep Space Nine) who gives the night its biggest laugh.

It comes when he names the one thing missing from his Starfleet jumpsuit: "Pockets."