The next two columns (C and D) contrast condom use between two different populations of gay men. The first were HIV-negative men in long-term relationships lining in San Francisco. Among them condom use was the exception not the rule, with only just over one in five couples always using them. Fifty per cent of couples ‘allowed’ sex outside the relationship, and the main purpose of the study was to see how couples negotiated rules around the safety ‘extra-marital’ sex and to what degree these rules were observed or broken.

In contrast, the second group of gay men – in column D – were gay youth (aged 15-25) living with HIV recruited in four US cities, who in the main did not have steady partners. The high condom use figure (82 per cent) was in fact even higher when it came to sex that carried a risk of HIV transmission: with partners whose HIV status was negative or unknown, condom use was 93 per cent.