Just one in 100 people in the UK say they are gay or lesbian, according to statistics on sexuality published for the first time today.
A further one in every 200 people are bisexual, according to the data published by the Office for National Statistics (ONS).
The information collected as part of the new Integrated Household Survey (IHS) means that nearly three-quarters of a million UK adults say they are gay, lesbian or bisexual.
More than 480,000 consider themselves to be gay or lesbian and a further 245,000 say they are bisexual.
The IHS is the largest social survey ever produced by the ONS and contains information provided by nearly 450,000 people - the biggest pool of UK social data after the Census.
Respondents were asked whether they would describe themselves as heterosexual/straight, gay/lesbian, bisexual or other.
Nearly all replied, with the vast majority (95%) saying they were heterosexual.
One in every 200 chose "other" and just under 3% said "don't know" or refused to answer.
The ONS said the highest proportion of adults who said they were gay, lesbian or bisexual was in London and the lowest in Northern Ireland.
The question about sexual identity was added to the survey last year to provide a fuller picture of British society and to help public sector organisations to monitor their responsibility to provide equal opportunities.
The survey also found seven in 10 (71%) people in the UK identified with the Christian religion, nearly nine out of 10 (89%) belonged to the white ethnic group, and four in five men (80%) and 78% of women considered themselves to be in good health.
All IHS statistics are considered experimental and are not yet submitted for assessment to the UK Statistics Authority.
ONS hopes the survey will become accepted as a national statistic by the authority in 2012.
The widely-held belief is that one on 10 people are homosexual.
Pioneering sex researcher Dr Alfred C Kinsey published research on the sexual behaviour of men and women in the 1940s and 1950s which said 10% of males were more or less exclusively homosexual but the figure dropped by around half in women.
Ben Summerskill, chief executive of lesbian, gay and bisexual charity Stonewall, said: "We warmly welcome these figures as Stonewall's pushed for this information for some time.
"However, this is the first time that people were asked and data collection happened on doorsteps or over the phone, which may deter people from giving accurate responses - particularly if someone isn't openly gay at home.
"Stonewall now works with 600 major employers and their experience is that these statistics increase when you regularly ask about sexual orientation as part of general monitoring information.
"We'd expect to see these figures increase over time as people's confidence in the survey grows and sexual orientation becomes a routine part of data collection."
A spokeswoman for the Government Equalities Office said: "We welcome the first ever official statistics on this issue and will be considering the findings of the ONS carefully.
"Regardless of how many people identify as being lesbian, gay or bisexual this Government is committed to protecting their rights and ensuring they are treated fairly by society.
"That's why, in June, we became the first ever British Government to publish an action plan to improve LGB and T (lesbian, gay, bisexual and transgender) equality."