Blackburn’s father, formerly a clerk in the merchant bank of Peter Muilman and John Berens (whose widow he married in 1789) became an ‘immensely rich’ government contractor, notably as the victualler of Gibraltar. In 1798 Blackburn inherited an eldest son’s share in the London business and in extensive estates in the home counties, in Hampshire, Gloucestershire and Cumberland.
Blackburn, whose father subscribed £10,000 to the loyalty loan for 1797, could be expected to support Pitt’s ministry, but he made no particular mark in the House. Perhaps it was he, described as ‘junior’, rather than his namesake the Lancashire Member, who opposed the land tax bill on 9 May 1798, but other hostile votes on this question were attributed to the county Member, who has also been thought more likely, from their context, to have made most of the speeches awarded indifferently by the reporters to ‘Mr Blackburn(e)’. This Member was the chairman of the committee to promote the petition against the return of Burdett for Middlesex, 6 Dec. 1802; objected to the mayor of Grimsby’s petition to the House, 5 May 1803, and on 27 Mar. 1804, as vice-president of the marine society, requested the committal of the fishery bill. On 1 Mar. 1803 he had taken six weeks’ leave for illness.
Blackburn, a steward at the Pitt Club dinner in 1808 and vice-president in 1815, evidently wished to re-enter Parliament, for he was an unsuccessful candidate at Poole in the by-election of 1809, on the interest of John Jeffery. He did not find a seat. In October 1819 he was a moderate alarmist on the question of a Hampshire county meeting.