I was given a model Swift for Christmas - must have been about 1958. It was mounted on a 12 inch length of flexible wire, encased in white plastic, that extended from the jet pipe to a rubber sucker. This was a representation of a contrail. Mine was mounted on a mirror in my room, and the wire adjusted to give the impression of two aircraft performing a manoeuvre in formation.
Funny that I can recall such detail over 50 years later ... or maybe sad!