Sorry, I know it's off topic but I have to ask , did you ever visit Diana at her various Gates of Hell flats ?
Her motif was a red ballon, had it on her phone box cards - One hell of a woman !
I may have done but don't recall a woman called Diana.
My main "cards in phone booths" period was 1992-99
Basement at I think 40 Gloucester Place (which is the side north of Marylebone Road) was somewhere I visited December 1992 and a bit beyond. The first woman I visited there called herself "The Flame" but said her name was Lisa and was very tough. There was also a girl who called herself April.
I was relatively poor then and a session typically cost £40, and I think they typically lasted about 30 minutes.
Later on I used to visit a woman called Lauren who worked in Riding House Street. On my 2nd visit she gave me what I think was the single hardest kick to the balls I have ever had. That was around October 1994, and I was just rolling around in pain. I visited another woman a few times at the same address the following year.
In March 1996 I visited a woman in Quebec Mews who gave my shins the hardest kicking I have ever received. I remained visiting that premises during that year, and her "maid" who was really the boss joined in at times. In early 1997 a young woman I had met there gave me her own number and I would book her privately and she came over to my flat, a couple of times with a female friend.
There was one I recall in 1997 who was very good but more expensive than the others whom I met the first time in Gloucester Place but then moved somewhere near Liverpool Street. Unlike others, she was independent - didn't have a maid answer - and took her own bookings.
By 1999, like most people I had a mobile phone and didn't use phoneboxes so I would actually prefer the quiet side-streets where I could look at a card and call the number on it from my own mobile. I had also already found a couple of them online even as far back as 1998.