OK Keith,

Sigma Research. An university of Portsmouth unofficial sex quiz with clipboards at Gay Pride in London. The Gay Men's Sex Survey - an online self-selecting sex quiz with no validation of the participants or academic rigour. Now dropped by Sigma because they worked out that it was meaningless and they admit to it all on their own website

Follow Keith's link and browse about.

The figure of 500,000 is not their assertion of the number of gay men, it is a big assumption about the number of men who think they will have sex with another man in the next 5 years. The idea comes from the national survey of sexual attitudes and lifestyles, which is only a survey of 11,000 people.

It found 8.6% of male respondents reported having had sex with another man.

Keith, you are a devious and untrustworthy piece of work. You rarely tell bald les, but you hardly ever tell the truth either, do you?

For what it's worth (which is not a lot) look at the discussion of the sexual attitudes and lifestlye survey

http://www.avert.org/gay-people.htm