There is an excellent film about his WW2 exploits in Gib. I can't remember its name but has an excellent under-water knife fighting scene versus the Italians and a great performance by Sid James as a CPO.
From what I remember, this was an MI 6 operation called on the spur of the movement, because they was wanted a look at the hull fittings of a SVERDLOV. (The only previous visit of the type to UK was at the 1953 Fleet Review, whereas this time, ORDZHONIKIDZE was alongside.) Rumour has it that he was captured by Ivan divers, taken aboard and waltzed back to Russia. There are stories that he stayed and trained Spetsnatz swimmers, and several books have shown photos alleging that this was "Crabski", but nobody on either side in the know would pass comment. Doubt if we'll ever know the truthon this one.
The more interesting guy to have been interviewed would have been Cdr J Brooks, RN DSO* (deceased), who was Crabb's attendant diver on the Ordzhonokidze recce. MI6 were certainly up to some very strange things at that period and the events surrounding Brooks later on are almost as intreaguing as those of Crabb.