The remaining members of Monty Python have confirmed they will perform together at London's O2 Arena more than 30 years after their last stage performance.
The veteran comedy troupe - John Cleese, Michael Palin, Eric Idle, Terry Gilliam and Terry Jones - announced the news at a madcap launch.
They promised the return of some of their most famous routines, including a likely performance of the dead parrot sketch, but Cleese has ruled out a re-run of one of his best loved moments, the Ministry of Silly Walks.
"I have an artificial knee and an artificial hip so there's no chance of that," he said.
Idle said: "I think you can expect a little comedy, a lot of pathos, some music and a tiny bit of ancient sex."
The show on July 1 is described as having "modern, typical, Pythonesque twists". Their last major live show was at the Hollywood Bowl in 1982.
"We'll be doing material we've never done live. There'll be quite a lot of that," said Idle, before pointing out that most people find new songs to be the low point of most concerts.
"We're hoping people will have forgotten so they'll appear new."
The Pythons have amassed millions of fans for their groundbreaking, anarchic comedy series and films, which also launched their own successful solo careers. And there has been excitement around the world after news of a possible reunion emerged earlier this week with the team supposedly entertaining bids to host the one-off performance.
The announcement was made at a press conference at London's Playhouse Theatre, where Python musical Spamalot is being performed.
Actor Warwick Davis, who recently appeared in Spamalot, hosted the event and poked fun at Fifa as he announced what was said to be the winning bid, claiming the venue would be "Qatar".
In typical humorous style, the quintet lined up behind the wrong name cards and they answered questions addressed to other members of the team.
Fittingly, the first question came from a Spanish journalist, with Palin responding: "We didn't expect the Spanish inquisition."
Asked why the reunion was being held now, Idle joked: "We're all trying to pay for Terry Jones's mortgage."
Cleese said "at first" the gig would be "a one and only" but did not rule out further performances.
He said Palin - who has gone on to become a celebrated globe-trotting TV adventurer - had "chickened out" of earlier plans to reunite and needed to be convinced about the plan.
Monty Python's Flying Circus was made for TV between 1969 and 1974 and generations of fans can recite lines and whole sketches. The team went on to make films including Monty Python And The Holy Grail (1975) and Monty Python's Life of Brian (1979).
Sixth Python Graham Chapman died of cancer in 1989 aged just 48, and nine years later the five remaining members shared a stage at the Aspen Comedy Festival in the US.
They said they would miss performing with Chapman but he would have a presence on-screen during the show.
Idle said: "We've told him we're going on and if there is a God, he'll be turning up."
The event will be filmed and "we will try and flog it later", he added.
Jones said the idea was sparked by a suggestion from South Park's Matt Stone and Trey Parker.
Speaking after the press conference, he said: "They said 'wouldn't it be nice to do something together' and that got us thinking and so we thought about doing something together.
"We'd like to do something with Matt and Trey but we'd like to do something ourselves".