Nr Fairy,
Thanks for that. I went flying yesterday, and remembering your experience I did more or less just that - monitored the RPM carefully as the governor took it up into the green. It occurred to me then that I should always have been doing that, as no instrument is infallable - but you do what you're trained to do unless you see a reason to change it. So many thanks for bringing this to everyone's attention. And having had one overspeed myself (and I agree, burning £50 notes would be a lot more fun
), I'm extremely concerned to avoid another one.