Simon
I keep it garaged, the condensation is on the inside. The guy I bought it off kept it garaged and it did the same when we took it out for a test. From other replies is appears to be a common problem. It does appear to reduce when the lights are on, proably heat from the bulbs drying things out. The speedo and revcounter don't mist up.
Had a good run round today and the wife has declared 'she likes it'

(providing I keep off the loud pedal

Andy