well that is the brazzies for you with their dodgy fuel Does seem a bit mad tho, going that small Evening
BTW I got to the bottom of my engine probs - dodgy dizzy! I going to have it to bits when I can be bothered, but the mech advance has crept up until it was 5 whole degs too much so I guess it's gradually fallen to pieces. The spark got so out of kilter on either 3 or 4 that it sounded like the piston was hitting the head even at tickover. Replaced the dizzy like for like, noise gone, flat spot gone, more oil pressure (must be cooler).