Bang on about

The term ‘bang on’ has been used to mean either ‘exactly on’, that is, physically close to, or ‘exactly right’. Those two meaning are exemplified here, respectively:

An advertisement in Punch April 1936: “Quiet garden square near Hyde Park. Real hot water. Bang on Tubes.”

(‘Bang on Tubes’ means ‘very close to an Underground station’. ‘Real hot water’ – who knows? Better than imaginary hot water I suppose.)

John Hunt and Alan Pringle Service Slang, 1943: “Bang on, bomber slang for ‘O.K.’ or ‘Everything’s all right’.”

These derive from an earlier American usage of simply ‘bang’, meaning ‘exactly’.

‘Bang on about’ has a different meaning though and doesn’t appear to be related to either of the above. It is a British coinage.

The Economist, October 1979: “Mr. Patrick Jenkin – Social Services – In cabinet tries hard but is inclined to bang on a bit.”

Julie Burchill, Sex & Sensibility, 1990: “This cry was taken up by the alt coms [alternative comedians] – Benny and Jenny and Lenny and Dawn – who would bang on about Reagan being an actor.”