I would give "James" untill the end of the week to sort it, then name and shameand look into a claim via the small claims court here and trying again with the fraud approach.
As well as the police you should contact Action Fraud
It is highly unlikely that a random number would be valid for an account on the same sort code. Simply giving a number out by one or two digits would not work as the IBAN would be wrong and the transfer process does a sanity check of this before the transfer even takes place, in effect it makes sure the account is valid before the money is transferred.
To me this smells like a scam. IMO "James" knows the owner of the other account and has appropriated the cash.
Even if ths is not the case, it is his error that has caused this and under UK law he is liable to either supply the goods or return the money,
The OP acted in good faith based on the information "James" gave him. In court this would be no contest.
If the case does go to small claims ( it's really easy to do and cheap or free) and you win then but he still refuses to pay up you can pass the debt to a collection agency along with "James" address details. You won't get the full amount, but will have the comfort of knowing that some big men in black overcoats will be paying him a vist and explaining very clearly why he should pay up. He'll also end up with a court judgement against him which will completely screw his credit rating for the forseable future. Again, doesn't get your money back, but maybe gives you some satisfaction.
I would give "James" untill the end of the week to sort it, then name and shameand look into a claim via the small claims court here and trying again with the fraud approach.
As well as the police you should contact Action Fraud
http://www.actionfraud.police.uk/
It is highly unlikely that a random number would be valid for an account on the same sort code. Simply giving a number out by one or two digits would not work as the IBAN would be wrong and the transfer process does a sanity check of this before the transfer even takes place, in effect it makes sure the account is valid before the money is transferred.
To me this smells like a scam. IMO "James" knows the owner of the other account and has appropriated the cash.
Even if ths is not the case, it is his error that has caused this and under UK law he is liable to either supply the goods or return the money,
The OP acted in good faith based on the information "James" gave him. In court this would be no contest.
If the case does go to small claims ( it's really easy to do and cheap or free) and you win then but he still refuses to pay up you can pass the debt to a collection agency along with "James" address details. You won't get the full amount, but will have the comfort of knowing that some big men in black overcoats will be paying him a vist and explaining very clearly why he should pay up. He'll also end up with a court judgement against him which will completely screw his credit rating for the forseable future. Again, doesn't get your money back, but maybe gives you some satisfaction.