Early life and family
Barnaby Backwell was the second but first surviving son Tyringham Backwell of Tyringham, Buckinghamshire, and Elizabeth, daughter of Sir Francis Child, lord mayor of London. He was the grandson of the financier Edward Backwell.
His daughter, Elizabeth Tyringham, married William Praed.
Backwell was a partner in the bank of Samuel and Francis Child, and said to have an income of £4,000 per annum. He stood for Bishop's Castle, a "rotten borough", in 1754. His uncle Samuel Child had been the M.P. in 1747-52. The borough was under the control of the Walcots who owed a great deal of money to Child's bank. Backwell came second in the voting. He was classed as a Tory in Dupplin's list of 1754.