Do you have more information than I have?
Short has been shown transcripts of a confidential talk. I do not see how she came to the conclusion that the British did the bugging. The best guess is that the locals did the bugging and let the British see some copies of transcripts to influence them in a certain way.

I'm not shocked at all, for 'shock' involves a certain amount of surprise, and I'm not surprised at all.

Wolfgang