Britain's most influential arbiter of public taste, the film censor, is predicting the end of legally enforced cinema ratings in the UK. In a speech on the future of censorship this week, Robin Duval will argue that greater freedom for film-makers and audiences is on its way.

We are pretty much the only country left to enforce a film rating system by law,   he said. In most of northern Europe and the Americas, film regulation is advisory and not mandatory. How long will Britain keep this up? As the internet and new media become more available, everyone wonders why one medium is regulated by law and another isn't.

Duval, director of the BBFC for just over two years, does not expect all forms of film classification to disappear. He envisages a grading scheme in which parents would be able to take children to seefilms they deem suitable. Existing legislation covering obscenity and child abuse would then become the only statutory public protection. In contrast, when the late Princess Diana controversially took an under-age Prince Harry to see the 15-certificate film The Devil's Own , the London cinema involved was threatened with prosecution under the 1985 Cinemas Act.

I suspect film producers will still want their product to be given some sort of bill of health, said Duval, but I think the legal nature of it will change fairly soon. Television will have to have its own ratings system too.

Duval will use his speech at the Royal Society of Arts on Wednesday to call on the Government to rethink its policy on monitoring broadcast standards. New Labour plans for one giant, over-arching watchdog to look after film, television and the internet are dangerous, he will argue, and are also based on false assumptions.

The Government's parliamentary consultation document on the communications industry, published at Christmas, outlined plans for a new body, dubbed OfCom, to take over the roles of the Independent Television Commission, the Broadcasting Standards Council, the Radio Authority, the Radio Communications Agency and Oftel.

Duval said: There would be too much power in one institution - a supreme cultural regulator. Video and film would be lost within the broadcast bias of this watchdog.

OfCom has been billed by the Government as a simplification of conflicting standards as the worlds of new media and broadcasting converge. But Duval and his colleagues at the BBFC, including the president, Andreas Whittam Smith, are not convinced by the argument that filmed entertainment will all soon be delivered via the internet. There are a lot of assumptions being made that people will gravitate towards their homes, said Duval. 'It is doubtful whether the expectation of this great convergence is justified. People want to have somewhere to go in the evening. There are actually now three times more people going to the cinema than in the middle of the 1980s. Duval believes it will take a long time for the internet to become a central part of the film business. Sport is still the driving force behind home satellite and digital ownership and no film channel yet receives more than 1 per cent of viewing figures.

Attitudes to sex on screen have been deliberately relaxed since Duval and Whittam Smith have been in charge at the BBFC. We carried out research into public attitudes last year and there was a clear message, said Duval. People believed the BBFC was being quite unnecessarily nannyish when it came to questions of sex, but attitudes to violence were less tolerant. The BBFC's rating categories would continue to be rigorous over violence. Duval said that although the link between people seeing violence on screen and committing it was poor, the BBFC had to respond to public feeling.

Public acceptability is one of the BBFC's main criteria for rating films. The only statutory restriction we have is on violence towards animals under the 1937 Animals Act. We also have some restrictions under the Obscene Publications Act, said Duval.

The BBFC ensures there is no mention of drugs in U-rated films. Even at PG level, however, there is more scope for referring to illicit substances, while at a 12-rating Duval says audiences are allowed to 'enter the real world', as long as there is no appearance of promoting drugs. Broadly, we have to steer away from "imitable techniques". And we will not allow any detail of a hanging in a 15-film, he said.

Duval believes he has seen the end of the recent tide of violent horror films. However, he is concerned that the industry is about to erupt into a spate of brutal adventure movies.

In contrast to current British concerns, American censorship has been tougher on sex than violence. In 1929 the Hays Office Code ruled that married couples had to be shown in twin beds and that one foot must stay on the floor in love scenes, lest the nation's collective morals were damaged.