Browsing You Tube I came across a BBC documentary from around 1970 called "Something for the children" - see below.
It starts well with a walking space toy, the Moon Scout, although it is a touch dull in places. High points are making the Clangers with Oliver Postgate and Peter Firmin.
I suspect of most interest to readers of the blog is an interview with Sylvia Anderson, where she talks in particular about why the characters had American accents (not just because of the American market!).
All the best,