Before there was radio control, model boating required a stout pair of waders. You went for a paddle!
A model boat valued at £100 in those days would now be just over £7000 today. I can't think of many models that would command that price, especially knowing how tight-fisted some model boaters are.
The boats are large to accommodate the steam power plants and I wonder how they were transported since so few people would enjoy their own car. I can't see fellow passengers on the bus being too happy and surely a trip on the tube (this is London after all) would be out of the question?