[1] Born in Yorkshire, the elder son of John Broadbent (1891–1963) and Hilary née Batty (1905–1998), he was educated at Oundle School.

Commissioned into the Royal Artillery as Second Lieutenant in 1945, he served as Assistant Adjutant at Dover Castle 1947-48, before leaving the Army to train as an architect (ARIBA).

Journalist Harry Eyres, who worked as a junior expert at Christie's, wrote that Broadbent "created a small niche of glamour for himself as a jet-setting wine celebrity, while everybody else in the office toiled in near Dickensian conditions".

[15] In July 2009, it was announced that Broadbent would sue Random House, the publishers of The Billionaire's Vinegar by Benjamin Wallace, an account of the "Jefferson bottles affair" and its court cases, for defamation of character, on claims that the book asserts Broadbent invented an auction bid and contains references to him colluding with Rodenstock.

[17][18] As Wallace was not party to the lawsuit or settlement, Random House continued to publish the book unamended, outside UK jurisdiction.