I am saddened by the fact that I able to confirm that it is indeed a Slingsby T67 Firefly that appears in "Come Outside" and that when they flew to Balamory they flew from Cumbernauld...
I have two nieces and I recently had to spend a week watching TV with them. It was easier to keep watching that than switch it over and try and stop them crying...
(I don't remember there being so many aircraft on TV when I was a kid!)