Thanks for the flattery. It's simple. Most of John's stuff is in D or G (or easily capo-able to one of them). There is only one note difference in the scales: the C or C#. So leave it out. Now if you play the wrong note (so long as it's in scale) it's a harmony, and if you're out of time it's syncopation or backbeat. Just watch the ins, outs, and tacets (bits where you stop playing in the middle of the song). Job done.

The stuff Brian is doing on mandola is actually lots cleverer than what I'm doing on mandolin, and if you really want to see a mandolin-player locally (Kent), go to see Cliff Bayliss.