Cheers everyone for your suggestions...it's moist, wet, low cloud and those sinister tiny little droplets that causes me probs....straight forward misting up on the inside of specs & visor clears as soon as I get moving properly
I think I'm going to get some daily disposable contact lenses again & just use them when I need them. I've had em before but don't really enjoy poking things into my eyeballs
....but they don't mist up, least ways not that I remember