The title is a mite misleading. But the author early on explains his motivations: this is the entire history, all the parts, nothing spared. ‘Spies beneath a number of tunnels’. ‘Spy tunnels are everywhere’. I’ve read of the ‘Berlin Tunnel’ and the Vienna Tunnels’ previously and didn’t have a problem with this telling. Non-Fiction, historical, spy-stuff: right up my alley. James Bond, Jason Bourne, etc, etc: it’s comedy. Blather. Ian Fleming worked on the fringes of SIS activity in Europe and his take on spy portrayal has always baffled me.
Overall, this is good stuff. It wanders from here to there, picking up threads and hoping to tie together, but it is all very interesting. Proper spying.