So Tom and Clive in the Orton diaries really were the same couple as 'T. and C.' in the Kenneth Williams diaries.

https://www.theguardian.com/film/2010/oct/10/kenneth-williams-biography-christopher-stevens

Although I've caught up to this rather late, I'm quite surprised; I assumed Russell 'No not him' Davies had disguised their names when he edited the diaries.