Thunderbirds - what is "FAB"?

…is it just “fab” like “things are fabulous”?

I just took my 6-year-old son to see it - it was pretty awful for me the adult, but he and his buddy really enjoyed it and are playing T-birds on the front lawn right now. Anyway, they use F.A.B. as a signoff for most of their communications without any explanation.

I did a Google check on it and gots lots of references to Thunderbirds with cute uses of F.A.B. - movie reviews saying the movie wasn’t FAB, or references to the FAB annual, apparently some sort of T-Bird convention, but no explanation.

The kids want to know and I admit, I am mildly curious - what is FAB?

PS: the character of Lady P was played by Sophia Myles - she was fun to look at for this adult…

According to Sylvia Anderson, who created the Thunderbirds TV series with her husband Gerry, “F.A.B.” was never intended to mean anything.

Er… am I the only person who thought that this was about Kim Wilson, Jimmy Lee Vaughan, Fran Christina and Keith Ferguson/Preston Hubbard, etc. etc.?