Fifteen years ago or so (I'm afraid I'm at the age when saying that means anything between 10 and 25 years ago) there used to be (sometimes) a 30-minute folk programme on BBC Radio-2 before (or was it after? Age again!) Mike Harding's Folk on Two.

At one stage Maddy Prior had the floor for a few weeks, and sang "Barring of the Door" amongst other things.

In introducing it she explained that the gentleman visitors were Reivers, who gave the English language the words bereave and blackmail. I haven't thought of it till now (memory's a funny thing: I can't remember the name of my nephew's girlfriend whom I met last Saturday, but this snippet of Maddy Prior's from 15 years ago seems indelible) and have just googled it. Found this site, which confirms what she said. I can understand bereave, but how does "Reiver" give "blackmail?"