Nearly one in five people are unhappy about the depiction of gay, lesbian and bisexual people on TV and radio, according to a report commissioned by the BBC.

A survey found that 18% feel "uncomfortable" or "very uncomfortable" with it, even after the 9pm watershed. Just under half of respondents said they were either comfortable or ambivalent.

Around a fifth of straight people said there was too much content relating to gay people on TV generally, although 46% said the volume was about right. Many lesbians felt there were not enough gay women on TV and most were portrayed either as "butch" or "lipstick lesbians".

Gay men said they would welcome a more realistic portrayal of gay life and criticised a tendency to feature camp men, though they said this was improving.

The research also found that landmark gay storylines were regarded as hugely important by gay respondents. Gay characters on soaps such as EastEnders and Coronation Street were also seen as important. The study is one the biggest of its kind, based on a survey of more than 1,600 people and discussion groups involving 500. A BBC public consultation had more than 9,400 responses. The findings will shape coverage for years to come and could lead to the introduction of more lesbian characters in the corporation's dramas.

Tim Davie, the BBC's head of audio, who chairs a working group on improving coverage of the gay community, said the research would help achieve more "authentic and diverse" portrayals. "The BBC has a responsibility to serve all our audiences as best we can and there are clear commitments we are taking from this study. We have already begun to share the research with content teams across the BBC in order to continue the progress we have made towards achieving more authentic and diverse portrayal of lesbian, gay and bisexual people."

Lesbians also felt there is was far too little coverage of gay female characters. The research also found that landmark storylines and "standout" moments on TV and radio are regarded as hugely important by gay respondents.

They include a rare pre-watershed on-screen kiss on Channel 4's Brookside in 1994, now regarded as one of the most memorable scenes in British TV history. More recent examples mentioned by respondents typically took place in dramas such as Channel 4's Shameless and Skins, and the US drama The Wire, which was broadcast on BBC2 last year. Gay men regarded Queer as Folk, another Channel 4 series, as the most influential show of its type, while lesbians cited Sugar Rush and Oranges are Not the Only Fruit, among others.

There was a recognition that soaps such as EastEnders and Coronation Street, which have prominent gay characters, also play an important role.

Channel 4 was widely praised for its portrayal of gay men, with 52% describing its coverage as quite or very good compared with 43% who said the same about the BBC's. Channel's 4's output was called "ground-breaking" by 44% of gay men.

Two previous Channel 4 series, Queer as Folk and Armistead Maupim's Tales of the City, based on the author's books based in San Francisco, were both singled out for praise.

Gay women said lesbians were often British broadcasters were guilty of portraying lesbians as either "butch" or "lipstick lesbians" and said they should follow the examples of their US counterparts, which they said programmes tended to convey a more nuanced view of the community.

The BBC will now make recommendations to the BBC Trust. They include introducing "incidental" gay characters whose sexuality is not their defining feature.