In a corporate-looking suite of the ExCeL centre, a softly spoken American tunes his guitar, clears his throat and breaks into song. The tune is a re-imagining of America's 1971 hit Horse With No Name, instead dealing with the dilemmas of exploring the universe: "I flew though the cosmos on a ship with no name..."

This is filk, a genre of science-fiction-inspired music named after a misspelling of folk, and one of the quirkier items on the agenda of the 72nd World Science Fiction Convention, which this year is being held in London.

The event brings together some of the biggest authors in sci-fi and fantasy, from Game of Thrones writer George RR Martin and Audrey Niffenegger, author of The Time Traveller's Wife, to 11-time Hugo award winner Connie Willis and British fantasy writer Joe Abercrombie. The organisers are predicting more than 8,000 visitors over the four days, making it one of the biggest WorldCons since the first convention in 1939.

Events range from author panels, to book readings, to talks exploring everything from How to Make a Dwarf Mammoth to Decontextualising Steampunk, via Gods in US Fantasy Television. On Sunday night, the convention will host the Hugos, the most prestigious awards in the world of fantasy and science fiction.

For those early risers, Friday began with a "stroll with the stars", an informal morning walk around the Docklands wasteland that surrounds the ExCeL with some of the most highly respected authors and figures at this year's convention.

Braving the gusty elements, a group of 50 wound their way through the roundabouts, Premier Inns and wire fences of the neighbouring City airport, and soon a discussion broke out about the unique world created at the convention every year.

"The thing with science fiction, it's a very different reader experience and I think this is the last convention in the world which is mainly about the prose," said Paul Cornell, an award winning comic book and screen writer who is nominated for a Hugo award this year and penned three episodes of the revived Doctor Who. (Steven Moffat, current lead writer of Doctor Who, was best man at his wedding).

"I like it because it's a very socialist enterprise. The only people who aren't paying to get in are the guest stars – that's five people. George RR Martin paid to come and in the past I've seen him queueing up. If they make any money it gets evenly distributed between all the people who appeared on panels."

The huge mainstream popularity of Doctor Who and now Game of Thrones, he said, had done vast amounts to change perceptions of science fiction in the past decade.

"I don't think people have that narrow view of sci-fi fans anymore – everyone's a geek nowadays," he added. "I do think there are deliberate efforts in some part of our culture to maintain the ghetto because we quite like it and it keeps us warm, but honestly those walls are completely porous now. In the 15 years between the old Doctor Who and the new one, it was like Russell T Davies [architect of Doctor Who's return] rubbed a magic lamp or something. The whole world has been changed into our paradigm."

Fellow author Mary Anne Mohanraj – who was a finalist for the Asian American book awards and is a member of Martin's collaborative fantasy fiction writing group, Wild Cards, along with Cornell – agreed.

"I think women in particular broke through some of these social barriers with that crossover," she added. "Whatever you think about the David Tennant sexiness, it changed things. The rise of the internet age has had a huge impact. People are not scared of geekdom in the same way, it's become pervasive in popular culture."

As the thousands flocked through the doors, queues formed outside the more popular events. Martin's reading of an unabridged extract from his yet unpublished history of Westeros, The World of Ice and Fire, drew hundreds into the auditorium to listen to the tales of bigamy, incest and an unfortunate end inflicted upon the poor stableboy, while in a smaller room, a debate on food in science fiction gets particularly heated over a discussion on turkish delight. The programme's variety reflects the multinational crowd with attendance records on Friday showing visitors from 54 different nations, including Venezuela, Saudi Arabia and Japan.

Iselin Stjernholm Uldal, 18, and Lars Boye, 21, had travelled from Norway. "I was raised on science fiction and fantasy, so it is amazing to be here," said Uldal. "I am a huge fan of Doctor Who in particular. But in fantasy books what I love is being able to go into a completely different world where everything is allowed and at conventions like this, the community is very accepting, so you can be as extreme as you want to and embrace this world as fully as you want to."

While most attendees save dressing up until Saturday night's masquerade, Jonathan Hall, 21, who studies physics at Oxford, spent Friday of the convention fully clad in a homemade Thor costume.

For him, while comics breaking out in the mainstream was "only a good thing" he said the big comic book and fantasy films made by Hollywood had a lot of catching up to do in terms of representing minority groups in the way the fiction and fan fiction did.

"I'm quite into queer fandom," Hall added. "I watched Doctor Who and Torchwood when it came back on television and being 14 at the time and starting to realise I was bisexual, having Captain Jack as a figure on television who become a role model in many ways was a huge help to me. So I think representation is really important and in many ways these big budget movies don't do it as well as books have been doing for a while."

Back in the makeshift Filk concert hall, the songs are still going strong. One, a lengthy acapella tune about the singer's experience of Swedish fandom, is set to the music of Scotland the Brave, and is followed on the bill by a singer under the name of Esgaroth3, has penned a comedic ukulele ditty mocking the introduction of a new elf into the Peter Jackson Hobbit films, called "Who the bloody hell is Tauriel?"

Willis, the most awarded contemporary science fiction writer, said as she wandered the convention halls, accosted by fans: "The sum total of all human knowledge is at every science fiction convention. They come from all walks of life they have a thirst for knowledge and a sense of excitement about the world and that everything is worth knowing and everything it's interesting. So my goodness, why wouldn't I want to be with these people?"