The other two are Allied Irish and Bank of Ireland, which is behind the UK Post Office savings accounts.

These two received a £6.5bn Irish government bailout last week, but remain independent. Anglo was wholly nationalised last month.

Anglo has been embroiled in several scandals, including allegations last Wednesday that it had 'cooked the books' to flatter its financial position last year. Authorities in Dublin are investigating.

While Allied Irish belongs to the FSCS, giving its UK savers the same protection as other UK banks, Bank of Ireland, like Anglo Irish, is outside the FSCS.

This has left the Post Office's 500,000 UK savers in uncertain territory. An unknown number - The Post Office insists it is small - have withdrawn their money amid worries over the safety of their savings. Unlike Anglo, the Post Office is not stopping withdrawals from fixed-rate bonds.

But as retired company director Ken Elston, 65, from Birmingham, discovered, the process is not easy. 'You can open the account in the post office in minutes and they'll take your money off you in no time, but when I wanted it back, my post office couldn't help,' he says. 'I was told to ring Bank of Ireland. Then, having done that, I was told to write a letter.'

He first asked for his money on January 26, but received the cheque only last Wednesday. 'In these uncertain times, every day matters,' he says.

Publicly, the Post Office insists that not belonging to the UK protection scheme is of little importance to its customers. But privately, executives are believed to be acutely embarrassed that because of its tie-up with an Irish bank it cannot offer its 500,000 customers the same safety enjoyed by savers with other UK banks.