Jim, sorry to hear of your troubles. Sounds like you, and several others, have run into a consistent scam artist.
I'm more familiar with the banking rules and regulations in the US, but have a working knowledge of the UK and EU as well. Bottom line is that if instructions are given by the account holder to deliver funds to another, the bank is not liable for a) fraudulent inducement of the account holder to initiate the payment, nor b) errors in the payment instructions provided by the account holder. a) is based upon common law, and b) is generally based upon disclaimers contained within the depository/customer agreement with the bank.
However, if the bank clearly failed in some gov't mandated security process that would have prevented the loss of funds, then you're likely to get the funds (and atty fees and related) back from the bank but it'll most certainly require a solicitor's help to force it if it's a meaningful amount of money. It'll be a (steep) up hill battle.
As far as where the funds may lay, you just know that the scammer does not leave scammed funds sitting in a bank account with known details (known by those who have been scammed). Two nanoseconds after those funds hit the Barclays account the scammer would have moved it elsewhere - for sure to a different country and legal jurisdiction.
And, you can be sure the scammer is not physically locatd in the UK. Believe it or not, there is a black market for legitimate open accounts in the UK. This is because there are (as was pointed out above) identification requirements to open an account. Typically, the person who opens the account does so with the purpose of "selling" the use of the account to someone else (who is a scammer) and then the account holder claims ignorance ("identity theft") as to use of the account when the law comes knocking.
These scammers are generally very sophisticated as to the details and nuts and bolts of scam. The funds are gone. All you can do is to try to show the bank did not comply with required procedures and insist (generally, with a solicitor's help) that their error allowed the loss to occur and therefore try to impose liability upon the bank.
Again, sorry to hear of your troubles. Stuff like that can drive you to drink!