I agree about the ready cash situation, my baptism was a second hand Hornby Dublo 3-rail collection, (Duchess of Atholl plus three, a working mail coach, an 0-6-2 tank plus two, and half a dozen assorted wagons, plus track) probably Christmas 1965 or 66, (wish I still had it!) but the receiving of train-set Christmas presents doesn't seem to explain the popularity of coarse (scale) models circulating mindlessly under Christmas Trees, which were presumably installed a few days before gifts were given.
Best
Simon