Thanks all, that's really helpful.
I have a Laco (nice big dial, minutes clear and easy to read) which does the job
except that it looses a few minutes here or there. It worked fine on the first nav but decided to fall 7 minutes behind just after I landed/refuelled. Probably needs a service after 6 years or I should have bought the more expensive model.
In any event, will look into the watch option or perhaps borrow my wife's jogging watch - hang on, there may be a GPS built into that?
Have a good bank holiday Monday if in the UK.
Corsican