Green’s Dictionary of Slang

excellent, perfect.

1966		Took & Feldman ‘Bona Books’ Round the Horne 20 Mar. [BBC radio] julian: We’ll call it – Vole Flanders, The Story of an Eighteenth-Century Water Slut. sandy: Fantabulosa!
1968		Took & Feldman ‘Ballet Bona’ Round the Horne 24 Mar. [BBC radio] Now look. Turn, Jule. Watch him, Mr. Horne. He’s on the turn. Now that’s beautiful. Isn’t that beautiful, that’s Fantabulosa.
2003		P. Baker [bk title] Fantabulosa.
2023		R. Milward Man-Eating Typewriter 4: A fantastic crime, a fantabulosa crime.