Gestapo Secret Police Nazi Rubber Ink Stamp in Period Nature Books. 1940s VGC. For Sale

This set of four books each contain a rubber inked stamp bearing the insignia of the Secret Police (Gestapo) in Berlin.The books came in a lot I purchased from a house clearance - the family had predecessors who had served in Europe during the Second World War.Since the publication date of these books is a little after the war ended, my best guess is that the rubber stamp was brought to Britain as some kind of war trophy, and subsequently used to stamp these books - this is purely conjecture - but the stamps appear genuine, and if an attempt was being made to mislead, then surely the stamps would have been used on more appropriate books or documents?The books themselves are in good vintage condition.Please see photos and message me with any questions.Thanks.