Hi all,
Many thanks for all the responses.
I've been out twice since posting, wearing the Nike Dry Fit shorts and I've used a little vaseline on the, ahem, affected area which seems to do the trick.
It's a little messy to apply

so I might check out that body glide stuff 'cos if it comes in stick form, it sounds a lot easier....I assume it's available from all good retail outlets..?????!!!
Thanks again.
Nick