It does sound a bit strange Peter, though compared with what Paul Foot is going through, you are having an easy time so far.
When you did the petrol-in-the-plughole trick, was the air cleaner fitted? If not, the whole thing sounds like a blocked air filter element. If the air cleaner was fitted, I'm wondering if you had a temporary blockage of the main jet, which has cleared itself. What happens if you put the air cleaner back on, now that you've had it running properly on its carburetor?
