Mark Forstater, who produced Monty Python and the Holy Grail, is fighting for an equal share with the Pythons in profits from spin-offs of the 1975 classic film, especially the hit live musical Spamalot.
Three of the six Pythons, Eric Idle and Michael Palin, both 69, and Terry Jones, 70, are due to give evidence in the five-day legal action at London’s High Court.
Mr Forstater is suing all three and the two other surviving Pythons, John Cleese and Terry Gilliam who are abroad and not expected to give evidence, for an increased share of the Spamalot millions.
The sixth member of the team, Graham Chapman, died in 1989.
A judge has been told it was the “worldwide commercial success” of Spamalot that appeared to have led in 2005 to a cut in the size of his share of the profits from Grail spin-off merchandising Mr Forstater enjoyed for almost 30 years.
Tom Weisselberg, appearing for Mr Forstater, argued that financially the film producer was entitled under an agreement made in 1974 to equal treatment with the Pythons.
But the Pythons said they could not recollect any agreement.
Mr Weisselberg told Mr Justice Norris: “The outrage expressed by a number of Pythons in their witness statements as to the suggestion that Mr Forstater was to be treated as the seventh Python is, with respect to them, misguided.
“There is no suggestion that Mr Forstater would be writing jokes, but what was being agreed was that Mr Forstater would share equally with them in the profit in the work they were together putting in to create the film.”
The Pythons were “unjustifiably attempting to secure more money from Spamalot at the expense of Mr Forstater and his company”, Mr Weisselberg added.
“Mr Forstater is in difficult financial circumstances and has been forced to bring these proceedings,” he said.
The film producer was made bankrupt in June. Last month, the bankruptcy was annulled and he is now involved in an independent voluntary arrangement (IVA) to deal with his debts.
The legal action is being brought by Mr Forstater and his company Mark Forstater Productions Ltd against Python (Monty) Pictures Ltd (PMP), which represents the film interests of the Python team, and Freeway Cam (UK) Ltd, which holds the copyright in the Holy Grail as trustee for those entitled to profit from it.
Mr Weisselberg said it was common ground that PMP was entitled to take 50 per cent of the merchandising and spin-off stream – “the top half” – from the Grail and not share it with investors in the film.
Mr Forstater had received one-seventh of the top half – the same share enjoyed by each of the Pythons – until 2005, when he was told he was only entitled to one-fourteenth.
Letters, invoices and the terms of the PMP agreement, and the evidence of two solicitors who were involved in drawing up the deal supported Mr Forstater’s claim for a seventh, said Mr Weisselberg. “They understood that, for financial purposes, Mr Forstater was to be treated as the seventh Python.”
If Mr Forstater wins his overall claim, it is unofficially estimated that – given the continuing success of Spamalot – it could eventually earn him a million-pound figure.
Created by Eric Idle, posters for the musical describe it as being “lovingly ripped off” from the Holy Grail.
Sheffield-born Palin is reported as referring to the money-spinning musical, which includes the hit number Always Look on the Bright Side of Life, as his “pension plan”. The hearing continues on Monday.