Ah someone at least as sad as me!!
Thank you Tim, you have clarified the markings on my tap. Big No 6 with a 32 in smaller letters; big and small are relative of course because the tap is rather small and a large magnifying glass is demanded to see the markings!
Personally, I don't think we're sad at all, David!
I have quite a large stock of M3.5mm stainless capscrews, so I retap to that size when I get a screw that's a bit chewed up.