A similar scenario perhaps !
A-G' Reference (No 1 of 1983) [1985] QB 182.
The defendant, a policewoman, was overpaid. The money was credited to her bank account as a result of an error by her employer. The evidence suggested that having discovered the overpayment, the defendant simply allowed the money to remain in the account. She was charged with theft of the sum overpaid but the trial judge directed the jury to acquit. The question of whether a charge of theft was possible in such a situation was referred to the Court of Appeal.
It was decided that provided there was sufficient evidence of mens rea, a charge of theft could succeed in such a situation. The defendant had got property (the excess payment) by another's mistake and was under an obligation to restore the debt (a chose in action) to her employer. Further, Lord Lane CJ suggested that s5(4) only started to operate from the moment the defendant became aware of the overpayment.