40mm UV Filter: Found one
(Moderators forgive if links are not allowed.)
I have been struggling to find a UV filter for the X10 and eventually found a post from someone who found a 40mm (and NOT a 40.5mm) UV Filter over at Japan Exposures.
I took a chance and spent the money (I hate, HATE having an exposed lens) and so I ordered and waiting and it arrived today.
And what do you know? It's an EXACT fit!
It's a little pricey - but my X10 is now safe.