Green’s Dictionary of Slang

(usu. UK juv.) an officious, domineering person.

1981		P. Wright Cockney Dialect and Sl. 115: Unless you watch your step, they may brand you a know-all, bossy-boots, clever-britches.
1989		A. Ahlberg Heard it in the Playground (1991) 100: Heard it in the playground / Bossy boots.
1999		Indep. Rev. 8 July 4: Bragg is apparently to be named to fill a customised corporate arts bossy-boots-at-large role.