Must be metal
...Following a spate of serious fire incidents with massive but poor-quality glass-fibre petrol tanks fitted to cafe racers in the Sixties and early Seventies the UK government outlawed the material for motorcycle fuel tanks. This draconian law had two effects on the UK market. First – in Bultaco’s case – was the loss of the super-slim tank seat unit in fabulous red and silver and the second was a bumping up of the cost to the customer. Bultaco importers, Comerfords of Thames Ditton, in Surrey, arranged for the manufacture of a replacement tank and seat unit in alloy and offered it for sale complete with Monza cap and padded seat as a bolt-on replacement. Manufactured by Homelite the first version was finished in a smart blue with a silver band running along the bottom of the tank part. A later version, most likely the same tank, had the silver continue up around the front of the tank. The cost of such law enforced updating? A snip at £19.95, which included postage, packing and VAT.