Re: Says it all
One of the reasons that Peter Wright saw Spycatcher banned was because he revealed some fairly sensitive stuff. I know someone who worked for the security services at the time (something I only found out about when they retired) and they confirmed that he hadn't just crossed the line he'd borrowed a Ferrari and gone way beyond it. I own a copy of Spycatcher and the reason for my friend going pale when they saw it in my flat way back around Christmas in 1987 when round for a quiet drink. The telephone tap methods he talked about, "Special Facilities" were much harder to implement undetected when people knew what to look for.
I looked at purchasing some flats in Notting Hill overlooking the Czech Embassy a fair few years ago. I asked about the history of them and why they were now on the market. The estate agent said he wasn't joking when he said they were very rarely available. MI5 had been using them round the clock until fairly recently to keep tabs on the denizens of the embassy.