Hello David,
I cannot be sure but Widney hold the largest market share of heater sales into mobile homes and Static caravans in the UK. As it is the most common make by a long way, the course may look at the Widney as the typical appliance, in much the same way that people often refer to 'Hoover' when they actually mean vacuum cleaner.
In touring caravan sales adverts the heater would be referred to as a 'Carver', again as it was the defacto manufacture for such appliances. In the UK up until 1999
Incidentally although Carver no longer manufacture touring caravan heaters, having sold that part of their business to Truma, Carver plc do own Widney, and Zig.