No? This suggests otherwise: the offence of handling stolen goods (Theft Act 1968 section 22) requires one to know or believe the goods to be stolen, and R v Hall 1985 clarifies "believe" for these purposes as the state of mind in which you don't know for sure they were stolen but no other explanation makes sense.

It seems clear to me that since two other explanations have been provided in this thread which do make sense and require no theft to have taken place (and which I'd guess are both at least as likely as my accidental theft scenario), I cannot be said to know or believe that the book was stolen and hence I am not guilty of handling even should it turn out to have been.

FWIW (and IANAL), I understand the situation in Germany to be something like this: it's not possible to obtain ownership ("Eigentum", as distinct from "Besitz" or possession) of stolen goods or counterfeit money, and if they are discovered, they will be confiscated and the police don't have to recompense you -- but you are, of course, free to bring suit against the shop that sold you those goods and demand that they give you something of worth in return for the money they took from you (or at least your money back).