Fascinating account of the secret ‘war behind the war’

As the tide gradually turned in their favour, towards the later stages of the Second World War, the Allies had several factors to their advantage from an intelligence point of view.

Firstly there was the cracking of the Enigma code by Alan Turing’s team at Bletchley Park – an operation that remained secret for decades, but has since been eulogised and mythologised.

Secondly – also at Bletchley – the equally difficult Lorenz Schusselzusatz ...