Neil, I thought about a fuel blockage/bad petcock..my head was spinning, trying to think about air, fuel, spark and compression...and what was I missing?? At home I could have cracked the carb bowl drain screws to check for fuel or even pulled the fuel line ...but on the road with no tools I felt a brief moment of panic. Also thought about something nesting in my airbox, fuel clog, coils? PUshing it home wouldn't have been too bad..but the last 30 feet up my driveway into my garage would have been a bear. I don't even think I could push almost 500 lbs up my steep drive.
I guess this is all part of the joy of riding a vintage bike. Moments of joy interspersed with brief moments of panic!