The Scammell Scarab did have a heater, although the problem was that you could not turn it off in the summer! Because the engine/gearbox/rear axle were in one unit, the engine was mounted immediately behind the cab. The radiator was therefore in the cab back panel and warmed (or boiled) the driver`s left side. With the radiator in the way of a conventional gear lever, Scammell decided in their typical unconventional way to put the gear lever on the driver`s right hand side and the tractor & trailer handbrakes between the drivers legs!

Thanks to Bill Aldridge, author of many books on old commercials.