Book #11 of the Papa Pontivy series.
The blurb on this adventure cries "McCarthyism comes to 1950s Britain". An English press magnate is starting his own version of communist-bating, pushing strongly for the establishment of a police state to combat this perceived problem. Papa Pontivy is suspicious and decides to investigate, with Bernard Newman's help. They will discover there is a major Soviet agent presence in the matter but the question remains what is the purpose?
Marshall is definitely a major player in this matter although he is said to again be working again in the Special Branch, still as a Superintendent .