Like the rest of the nation, Dr Roy Robertson has been watching It’s a Sin, Channel 4’s drama series about young gay men and the Aids epidemic of the 1980s. Yet when this tall, softly spoken man watches the scenes unspool, he cannot help but be tugged back to a decade when, as a GP in Edinburgh’s Muirhouse, he did pioneering work on the disease and its transmission among the city’s heroin addicts.

“I thought the drama was terrific. It really brings back the reality of what it must have been like to be a young gay man in the 1980s, when everything was against you and the stigma was massive. But it also brings back that interesting insight into the support group that