Eleven-year-old Effie is tinkering with the design for the embroidery which surrounds an online photograph of Felix the cat. She has been coming to this club for about a year now – her mother, Wendy Lynch, a web designer, is a volunteer who helps the children set up their own computer games.
Wendy freely admits that Effie is now more advanced in her use of technology than she is. Effie agrees with her. "I was interested in the idea of coding and helping the kids to create their own computer games," says Wendy. "We're just here to help them if they don't get it or understand it."
As Effie and her pal Klareze Wong, also aged 11, nimbly click away at their computers, there seems little danger of that.
Welcome to Code Club, an extraordinarily successful after-school club which was set up to help children aged between nine and 11 develop their computing skills.
Members devise their own computer games, create their own animations and learn how to use technology creatively.
Effie and Klareze spend one evening a week at the club in the basement of a primary school attached to Soho parish church in the – you've guessed it – the Soho district of London.
It is one of 25 similar clubs that acted as a pilot for the programme – which now encompasses 900 clubs in the UK and operates in 120 schools. Now it has announced it is expanding overseas with the launch of Code Club World – which has already excited interest in countries as far apart as Spain, Norway, India, Brazil and Ukraine.
The project has received a ringing endorsement from the father of the worldwide web, Sir Tim Berners-Lee, and the Duke of York has lent a hand with its marketing.
When the project was first established, it received the backing of Google and microchip maker Arm Holdings.
Computer programmer Clare Sutcliffe founded Code Club in April 2012 with web designer Linda Sandvik. "We were aware that teachers didn't teach children to code in schools," she says. "It is not something teachers know how to do. We had to go for an age group that had literacy and maths and were abler to get on with doing projects by themselves."
Up until now, she added, technology lessons have been more about showing pupils how computers work rather than understanding how they work and using them to develop programs.
The wind of change is blowing, with Education Secretary Michael Gove paving the way for a more rigorous computer science approach to the teaching of technology.
But there is still a question mark over whether many teachers will have adequate knowledge to adopt this new approach to delivering the curriculum.
"In fairness, they have changed the curriculum so that it now does not just focus on how to use ICT (information communication technology)," says Clare. "It includes a lot more computer science now. It includes using the software creatively. I know that is changing but I'm still slightly concerned that the majority of teachers aren't prepared for the new curriculum."
So there will still be a place for the kind of innovative computer learning the children who attend her clubs get during their weekly after-school sessions.
Each club has around 15 children enrolled – which means approximately 13,500 children are taking advantage of it nationwide.
"It is all across the UK," Clare says. "There is one in the northernmost tip of Scotland and the highest club-per-capita ratio is in North Wales – one guy has gone round all the schools to see if they would like to set one up."
One of the spin-offs from the clubs is that they have helped children who take part become the technological equivalent of pen-pals with young people of their own age in different parts of the country.
There will be scope for interaction with clubs in other countries across the globe as Code Club spreads.
"The way we operate abroad is slightly different," says Clare. "We support the people who set the clubs up but we won't be running the clubs ourselves. It would just be too much."
Initially, Code Club spread by word of mouth and there was a lot of activity on Twitter – which extolled their virtues and led to the demand for new clubs to be set up.
The clubs need volunteers like Simon Wharton, a computer programmer who helps out at the Soho club, to take charge and help the children out.
The whole experience can push both volunteer and child "out of their comfort zone" as they experiment with new ideas for programs.
"This is something I wouldn't get to experience in my job," says Simon. "It is not the same as showing people computer programs. The kids' eyes light up and ... when it clicks with them it is incredibly rewarding."
Simon, though, is well aware that he is not a teacher. "I can show them what to do but I've never been taught how to control them – or anything like that," he says.
It doesn't seem to matter much from the way the pupils are working on their own but there are plans to get the help of a teacher next term.
Back to the children, though. Nine-year-old Sabiha Malik may be one of the youngest at the club but she has already progressed to designing her own games – and has been at the club for just over a year.
"I like being creative and I like making games here," she says.
Effie is adamant the time she has spent at the club has helped improve her ICT skills. "It has improved me a lot," she says. "In school we're told about how the computer works but we're not really making anything on our own – because the work that we're given is the same as everybody else in the class.
Klareze adds: "It is very nice for a child to learn adult stuff because loads of people don't get that kind of opportunity. I now know more than my mum about technology."
From modest beginnings, Code Club has become a full-time occupation for Clare and her co-founder, Linda. They expect to more than double the number of clubs operating with the expansion around the world.
It is, though, for them, still a labour of love.