Sowerbutt's Robbery

"One of the bosses at New Scotland Yard has a theory about the Croydon robbery. They got away with a fortune ˗ more than £200,000, not that we’re letting on. He thinks it is an underground Blackshirt group, planning to use the money to finance some sort of pro-Jerry coup."
https://www.amazon.com/Colour-Red-Deal-Sowerbutt-Novels-ebook/dp/B00RL9FGKM?