Yes, I think those in his life, especially his wife, must've known. And there is historical evidence in other artifacts, but it's no surprise that conservative critics would've ignored those particular artifacts or didn't know about them.

Highly recommend "The Flight Portfolio"! Though it is fiction in some ways it's more non-fiction for having acknowledged more of the psyche of what may have been going through Fry's mind, by accepting that he was gay. I'd argue that what he accomplished was partially due to the fact he was gay.