Closing ceremony promises 'cheeky, cheesy' end to the London 2012 Olympics

British music and comedy will be the focus

London will say farewell to the Olympics tonight with a "cheeky and cheesy" celebration of the best of British music and humour. The world's athletes will gather together in something akin to a giant circular mosh pit to watch a display that its organisers are already saying will be "the best after-show party there's ever been".

The four-time gold medallist Ben Ainslie – who ran the first leg of the torch's relay around the UK – will lead Team GB into the stadium tonight as the country's flag bearer. Ainslie, who became the greatest sailing Olympian of all time when he won his fourth consecutive gold medal last week, said: "It's a really proud moment for me and for sailing to have such an involvement at the end of what's been such an amazing Games for the whole country."

From 9pm, some of the biggest names in 50 years of British music are expected to perform, including George Michael, the Pet Shop Boys, Muse, Jessie J, Tinie Tempah and Ed Sheeran. The show will take people on a journey from Elgar to "Waterloo Sunset" in 30 tracks.

Although national flags will be brought into the stadium in a procession, the athletes themselves will intermingle, so they can watch the show together. At the end of the evening, the flame that has been burning in Thomas Heatherwick's cauldron for the past fortnight will be extinguished in a spectacular finale.

More than 4,100 performers will take part, including 3,500 volunteers and 380 schoolchildren from the Games's six host boroughs.

The heart of the ceremony will be an hour-long section called Symphony of British Music, where the London Symphony Orchestra will be joined on stage by a roll call of the greats of British music. It will not be the showbiz treatment that most of the stars are used to: each has been paid £1 to take part and none of them will be introduced on to the stage. Instead, the show will be a seamless performance of music, dance and comedy.

It already looks as if the closing ceremony will be as unashamedly British as Danny Boyle's opener, with few concessions to foreign audiences. Eric Idle is expected to sing the Monty Python song "Always Look on the Bright Side of Life" and David Jason and Nicholas Lyndhurst will reprise their roles of Del Boy and Rodney Trotter, with their Reliant Robin van reportedly being blown up in a sequence in which they pretend to be Batman and Robin.

Famous London landmarks including Tower Bridge, the London Eye, Big Ben and St Paul's Cathedral have been reconstructed for the action. The Spice Girls will reunite to pay homage to their Noughties heyday, standing on top of distinctive London taxis. Footage of highlights from the Games will also be incorporated into the proceedings, as well as the men's marathon medal ceremony and parting speeches from officials. With only 21 hours to prepare the stadium for the show, there will be little time to plan a spectacle on the scale of Boyle's opening, which took days to build. But the creative minds behind the show believe it will still be a night to remember.

Kim Gavin, the artistic director, said in a press conference yesterday: "I want it to be the best after-show party there's ever been." Talking about the jumble of music they had put together, he said: "It's a mashed-up symphony, and the symphonies go in all sorts of different directions."

He paid tribute to the 3,500 volunteers taking part, saying they had slogged through rehearsals in all weathers at the Ford car plant in a "very windy" Dagenham. "It's rained every single day," he said.

Eight minutes of the show will be set aside to allow Rio to show what it can do. Gavin said: "I think it's a gift that we've got Rio next, because that eight minutes will be wonderful and full of that samba beat."

Between 200 and 1,000 extra seats will go on sale online today.