FAQ for
"Thunderbirds" (1965) More at IMDbPro »

...absolutely nothing.

The definitive answer came from Sylvia Anderson herself during a promotional tour of her book. It was something they made up on the spur of the moment during a writing session, Sylvia says, and it was never intended to stand for anything other than to spell out the letters of a popular British slang word--"fab"--during that era. Many people have attempted to find other meanings ("Filed, Actioned, Briefed", "Fine--Acknowledge Broadcast"), but it never meant anything other than "fabulous".

Yes it was. The character was originally envisioned as the blond, blue-eyed hero, but Gerry Anderson was unhappy with how the puppet for John Tracy turned out, branding it ugly. So he was put aboard International Rescue's space station Thunderbird 5, presumably as once he took the emergency call in each episode and relayed it to Tracy Island, he wouldn't be seen again, thus keeping his screen time down. In fact John only takes an active role in one rescue in the series, in the episode "Danger At Ocean Deep". It is also worth noting as surely no coincidence that in the one episode that relies on heavy contact with Thunderbird 5, "Operation Crash-Dive", Alan Tracy just happens to be taking his turn aboard the station!

Yes. The first nine had already been scripted, shot and edited as 25-minute episodes (as were previous productions such as "Stingray") when the Andersons' backer, ATV head Lew Grade, sat down to watch the completed pilot, "Trapped In The Sky". He was so excited by the results that he immediately demanded that all episodes be increased in length to fill an hour-long TV slot. As a result these nine episodes were re-edited with extra footage to fill them out. Ironically, when the show was eventually sold to the American market, the entire series of 32 episodes had to be edited into 64 half-hour shows, due to a lack of hour slots in the US TV schedules.