Decimus was the 10th child of the property developer James Burton (formerly James Haliburton)[REF] and Elizabeth Westley (12 December 1761 - 14 January 1837), of Loughton, Essex, daughter of John and Mary Westley.
On his father's side, his great-great grandparents were Rev. James Haliburton (1681-1756) and Margaret Eliott, daughter of Sir William Eliott, 2nd Baronet and aunt of George Augustus Eliott, 1st Baron Heathfield.