After reading about ppl changing the fuel lines without pulling out the carbs I decided to investigate further - I pulled one of the fuel lines off thinking I could flip them and put the loose ends at the petcock with clamps. But, after removing one, it didn't seem like it was loose enough to have been leaking as it was so hard to get off...
I connected a fuel supply to the other one, and.......no leak!? Then I spend a loooong time teasing the 1st one back on by poking at it with various implements to induce it to twist on while pushing and twisting it from behind the hole it passes through and hooked up fuel to it and.... also no leak despite damaging it and not quite getting it all the way back on!
So I thought the extra pressure of a full tank would make it leak, put the tank back on hooked everything back up and turned the fuel on. After 15 minutes..... still no leaking?
I have concluded that I was mistaken and it was actually the T joints between the carbs leaking. The weather was particularly hot and dry in the week and a half that I didn't use it, so I guess the o rings on the T's dried out and shrunk but after a good drenching slowly swelled back up to not leaking status... (I've never had this problem with my unrestored carbs!)
Lesson I learned is to ride my bike often, at least every week, preferably every day!
John