Green’s Dictionary of Slang

very attractive, excellent.

1959		I. & P. Opie Lore and Lang. of Schoolchildren (1977) 181: Other superlatives in favour were: bang on, beezer.
1984		Partridge DSUE (8th edn) 6/2: since ca. 1935.
1999		Indep. on Sun. Rev. 21 Nov. 7: Brilliant! Down to 1,000ft over the Dome. Beezer!