Brettell was born at Sutton-in-Ashfield, Nottinghamshire, on 16 April 1793. His father, Jacob Brettell, became a Calvinistic preacher at the age of seventeen, and after serving various chapels became an independent minister at Sutton-in-Ashfield in 1788.
He also kept a school (see notice by a pupil, East South Peacock, in Notes and Queries, 2nd series, xi 378). He died 19 March 1810. A public subscription, aided by the vicar of Gainsborough, provided for his continuance at York till 1814.
He became Unitarian minister at Cockey Moor (now called Ainsworth), Lancashire, in July 1814, and removed to Rotherham in September 1816.
He resigned in June 1859 from failing health. Brettell is described as a good scholar and effective public speaker.
His poetry shows taste and feeling. His later years were tried by adverse circumstances.
He died 12 January 1862.
