Ok folks, the answer was player A had 55, Player B had AJ (fairly easy to guess).
I was player B.
So, how do we reckon the respective hands played it? Was it by the book?
I think player B got it right. Although in all fairness he had it easy. He could be pretty sure he wasn't facing a pair of Jacks, so he was in a good position after the flop.
After the turn Player A's bet of £1-50 was 'wrong' ,and this is a great example as it's highlighted what I'd do.
My thought process previously would be. Hmm, I've got 3x5s, which is pretty good. Player B could be on 3jacks which would beat me. So I'll bet a middle amount of £1-50.
Player B, sees this as a sign of weakness, confirming he's not up against a full house and proceeds to the bounty. ( I might as well have had a big sign on my head saying 3x5s).
What player A should have done after the turn is fold, or put down a huge bet. Even that might not work as to be consistent they should have put down a bigger bet before the turn.
Either way, there's no way I could have figured that lot out in the limited time you have online. Harrington's work should be revisited with a view to making these decisions faster.
All of this ignores bluffing possibilities, but without being at the table and seeing previous play, there's no way we can assign appropriate probabilities.