I was surprised and ultimately disappointed with this book.
With the author being Nigel West I did expect it to be more or less as his others, a good story and read.
All this is are files that have been released by whoever and made into a book. It will only be of interest I believe to someone who is studying the Cambridge Spies for research as it is not a story as one would think.
A far better read is 'Treachery' by Chapman Pincher of the same people. It is an in depth story of the Cambridge Spies and update with official papers that have been released over the years.
Better still now is 'GCHQ' by Richard Aldrich, an update on most of Pincher's comments.