He regards the rates paid to savers - or charged to borrowers - as a commercial matter outside his powers.
Now for the first time he has upheld an investors's complaint about the rate paid on a building society investment.
A society offered a highly attractive rate on a two-year bond. But the rate was variable, and before long the rate was cut to below that paid on any tier in the society's 90-day account.
Investors were forbidden to touch the last pounds 10,000 in the bond. The Ombudsman regarded the terms as unfair and ordered the society to pay the difference between the rate paid on the bond and the 90- day notice rate. More than 30 investors received payouts of between pounds 9.83 and pounds 1,400.
A complaint involving Alliance & Leicester's Gold Plus, Ready Money and Ordinary Share accounts is still under consideration after the society decided not to go ahead with court action to stop the Ombudsman looking at complaints.
Building Societies Ombudsman, Grosvenor Gardens House, 35/7 Grosvenor Gardens, London SW1X 7AW 071-931 0044.Reuse content