"that phrase delinates the distinction between fiction and fantasy."
I think any SciFi story that requires FTL would disagree with you.
"Suspension of disbelief" is the willingness of the reader/viewer/consumer to allow the story to work on its own terms.
I don't think there's _any_ SciFi that doesn't require some level of suspension. It may be minor (eg Allen Steele's near space stories) or it may be major (Star Trek, Babylon 5),
Or even your Thunderbirds; really, a rocket ship launching from the swimming pool without setting fire to the whole island? Have you seen how far back the safety area is at Kennedy Space Center? Tracey Island would be obliterated first time Thunderbird One launched.
We ignore these "errors" because they don't get in the way of the story. We deliberately suspend our notions of reality to aid in the story telling process.
And it doesn't matter the genre. If it's fiction then it requires some level of suspension of disbelief. Do you really think that any best selling book doesn't require acceptance of the universe? Even a Barbara Cartland "romantic" novel requires the acceptance of some super-stud Italian... and let's not get started on '50 shades of grey" :-)