Green’s Dictionary of Slang

precisely, accurately; usu. as bung in, bung on.

1898		Kipling ‘In Ambush’ in Complete Stalky & Co. (1987) 16: Thought you were stalkin’ us, eh? Why, we led you bung into it, of course.
1904		Kipling ‘The Bonds of Discipline’ in Traffics and Discoveries 72: A week o’ similar manoeuvres would ’ave knocked our moral doublebottoms bung out.
1937		E. Raymond Marsh 231: It’s the ground-floor front room, bung on the pavement.
1949		‘Josphine Tey’ Brat Farrar 62: ‘It’s quiet here. And handy. And bung full of privacy’.