Just one in 100 people in the UK say they are gay or lesbian, according to statistics on sexuality published for the first time.
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.