NIB gave us a mortgage on a buy-to-let in Northern Ireland last year. We took the mortgage in euros. The advantage at the time was that the ECB rates were a good bit cheaper than the UK interest rates, and still are cheaper. However there is an added risk with currency exchange rate, so that could be a potential down side. NIB told us at the time they were doing it as a one-off for us, but I don't think we're that special, so I'm sure they must do it fairly regularly. It might be worth your while to contact a good broker to find out which banks do this, as that's how we were put in contact with NIB.