Details of Bates early life are sketchy. He was born around 1736, somewhere in the North of England and is was to have studied medicine in Edinburgh, though Benedict Nicolson, states that there is no record of a Benjamin Bates graduating in medicine from Edinburgh University at that time. Bates lived in Derby for a time, either as a child or after his studies.
Around 1758 he bought a house at Rickford's Hill, in Aylesbury in Buckinghamshire, and set up as a general practitioner. He was married twice and had one daughter, Lydia. He may have worked as Sir Francis Dashwood's personal physician; he is referred to as such in Jemmy Twitcher, George Martelli's book on John Montagu, 4th Earl of Sandwich, and certainly intended to accompany Dashwood in the role of physician on a tour of Europe. Sometime before 1774 Bates moved out to Little Missenden, though he kept his practice in Aylesbury.
Bates lived a life of excess which included joining the Hellfire Club at Medmanham. Membership of the club can only be guessed at, as only patchy, pseudonymous records survive, but despite apparently having become a member in the "second wave", E. Beresford Chancellor places Bates in the ranks of the superiors in his 1925 The Lives of the Rakes: Volume IV, The Hell Fire Club, alongside Sir Francis Dashwood, Sir Thomas Stapleton, Sir John Dashwood, John Wilkes, Charles Churchill, Paul Whitehead, Robert Lloyd, George Bubb-Dodington, George Augustus Selwyn, Sir William Stanhope, the Earl of Sandwich and Sir John D'Aubrey. Long after scandal and ridicule had forced the club into abeyance Bates continued to defend it.
Bates was patron of the arts, buying important works by Joseph Wright of Derby (Three Persons Viewing the Gladiator by Candlelight and An Experiment on a Bird in the Air Pump) and by his close friend, John Hamilton Mortimer (St Paul Preaching to the Ancient Britons). In 1781 he gave up his practice in order to accompany Sir Francis Dashwood (by this time Francis Lord le Despencer) on a tour of the continent. Unfortunately Dashwood died before the trip began and Bates did not receive the huge annuity promised him for his services. Nevertheless he was still intent on visiting Europe, Rome in particular, and made a tour to Italy in 1787 accompanied by his daughter.
He died at his home in Little Missenden on 12 May 1828.
- A commemorative tablet in the floor of the church in Little Missenden puts his age at his death in 1828 at 92, but there has been no independent confirmation of his birth date.
- Nicholson, Benedict (1968). Joseph Wright of Derby. The Paul Mellon Foundation for British Art Patheon books.
- Chancellor, E. Beresford (1925). The lives of the Rakes: Volume IV, The Hell Fire Club. London: Philip Allan & Co.
- "John Hamilton Mortimer and the discovery of Captain Cook". National Library of Australia. Retrieved 23 May 2007.