Interesting what you say about the Pay Book. But surely that was just the soldier's own record. Central records were also held, and it's those records that the MoD stores, and can send you (if approved, and paid for). My father's (duplicate) Pay Book has very little, as he did NOT get on the boats at Dunkirk, but spent 4 years PoW in Poland, having been captured at Calais. I'm assuming they destroyed their Paybooks before capture - so that they only gave "Name, Rank, and Serial Number"..