Is a bank allowed increase mortgage interest rates at times when the rates set by the European Central Bank (ECB) are historically low?

That is a question the Financial Services Ombudsman is going to have to review after a High Court ruling.

Kenneth and Donna Millar have seven mortgages with Danske Bank - all on standard variable interest rates - dating back to 2005.

Last year the Financial Services Ombudsman found under its loan agreements Danske was allowed hike interest rates to over 4% at a time when ECB rates plunged to almost zero.

Danske argued that it does not receive ECB funding, and so the cuts were irrelevant.

But the Millars complaint will now have to be reviewed by the Ombudsman following a High Court ruling, which found a clause in the bank's loan agreements - that interest rates are altered 'in response to market conditions' - to be ambiguous.