This one really is a "pet" peeve, as I suspect that it is me that is out of step, rather than everyone else, but it still irritates me when I hear it:-

If the Bank of England announces an interest rate rise from, say, 2.25% to 2.5%, I would say that there has been a rise of a quarter of a per cent. The BBC would announce that there has been a rise of a quarter of one per cent. All the other TV channels do the same, which makes me think that I am wrong but I don't care - I am going to carry on saying it the way I want to.

DC