Howard Marks is counterculture Britain's answer to a Renaissance man: an Oxford-educated drug smuggler and libertarian with a strong rebellious streak. His autobiography, Mr Nice, chronicling his journey from a small village in Wales to Oxford University and his subsequent emergence as, in the words of one UK newspaper, 'the most sophisticated drugs baron of all time', is now, after several false starts, being made into a film.

'It's the personality of Howard, the humour that's in there, the big range of emotions that lend themselves to a film,' says producer Luc Roeg of Mr Nice, which shot for eight weeks on location in Wales and Spain earlier this year. '[Marks] is a pillar of the anti-establishment. We know we've got a great story and films are about telling great stories.'

Rhys Ifans stars as the maverick cannabis trafficker who claims to have been connected with everyone from the Mafia to the CIA and who ended up serving seven years in one of the US's toughest prisons. Ifans heads an eclectic cast that includes Chloe Sevigny and David Thewlis, while Philip Glass has been brought on board as composer. Roeg's company, Independent, is also handling sales on the film.

E1-owned Contender Films is the UK distributor, and Independent and Prescience are the majority financiers of the $8.3m (£6m) project. The first footage will be screened in Cannes, with the film-makers hoping to premiere it at a festival in early 2010.

Roeg is at pains to point out this is not 'a parochial British story'. Marks is an international figure whose autobiography has been published all over the world. The ex-drug smuggler has thrown his support behind the film, which spans three decades.

A meeting of minds

In director Bernard Rose, Marks perhaps recognises a kindred spirit - a film-maker who shares his anarchic side.

Rose, whose credits include Ivansxtc, The Kreutzer Sonata and Immortal Beloved, was first brought in as director of Mr Nice when the film was in development several years ago at a UK TV company.

He is withering in his assessment of the double standards he believes cloud UK attitudes toward illegal drugs.

'What Howard represents is something very honest - the truth about the history of drugs in this country,' the writer-director reflects. 'The mistake is to confuse a film about drugs with a film about addiction. The two things are different issues and different stories. That's where the confusion comes in. Howard's story is about liberation and freedom.'

Ifans steps in

Rose wrote the screenplay with Ifans in mind. 'He was someone I knew socially and there was really no-one else you could imagine in the part,' he says. 'From the very beginning, I always wanted Rhys.'

[The director likes to bill the film as 'the Lawrence Of Arabia of stoner movies'. It has comic but also tragic aspects. And Rose says he is not out to provoke controversy for its own sake or to sway opinions about drug laws. 'I don't think it's a crusading film. It's taking a look at where the history is... obviously, there is a tremendous amount of hypocrisy involved (toward drugs).'

Rose - who shot his more recent films digitally - is making Mr Nice on 35mm. 'I'm trying to shoot 35mm with the same disrespect that I would shoot digital,' he explains.

It is more than 20 years now since the director made his feature debut Paperhouse (1988) and was touted as one of UK cinema's great new hopes. Since then, he has made everything from horror films (Candyman) to literary adaptations (Anna Karenina) and a film about Beethoven (Immortal Beloved).

'The government is too involved in movies in the UK,' he reflects. 'That produces a certain kind of movie. There's a pressure to be worthy and PC here which is a shame for the industry. It would be nice if there was just more freedom.'

These constraints do not just apply to the film industry but - Rose suggests - to UK society as a whole.

'One of the things that shocked me coming back here is how many laws there are. There are laws about sneezing, parking and driving your car. Britain has become more repressive than it was even in the Victorian age in terms of how many rules and laws there are trying to control people's behaviour. It's unbelievable how far the British have gone in that respect. You can't imagine them doing anything like legalising drugs. But, of course, most of the English people I meet are high all the time!'

Mr Nice is an epic of sorts. 'It's just trying to tell the truth. The idea that you can be for or against drugs is an absurdity. Drugs are just a simple fact. You can't be for and against something that is a fact.'