Foreign property: debts: bank accounts
A bank account is a debt, and under general law is situated at the branch of the bank where the account is kept: R v Lovitt  AC 212.
This general law rule may be modified for Inheritance Tax (IHT) purposes by a Double Taxation Convention.
Any case where it is claimed that a bank account in the UK must be treated as situated abroad (so it is exempt from IHT) must be referred to Technical. But you should remember that some foreign bank accounts can be excluded property and not taxable for IHT purposes (IHTM04380).