I know you must be among these somewhere Madge but, by the sounds of them, they were run on "Tin-Tacks" and not petrol. I note the Black and Amber one in the opening shot:
Nick, who does Hull's tenfootcity magazine has a really nice amber and black Lambretta with 'Easy Tiger' sprayed on the cans(I can't find a pic of it, he sent me one once, but I can't seem to find it).