Captain Barclay's most famous exploit took place between 1 June and 12 July 1809 at Newmarket, during which he walked 1 mile (1.6 km) in each of 1000 successive hours, to win an initial wager of 1000 guineas. The enterprise quite caught the public imagination. "The Times", which carried little in the way of general interest news, printed this report alongside an account of the campaigns of Marshal Soult in the Peninsular War (14 July):  During the 42 days of this exercise, his time per mile increased , while his weight dropped (186 lbs) (154 lbs). If the report of the total wagers was accurate, they were equivalent to some £5 million ($US 8 million) in modern terms. The first woman to successfully emulate his feat was Emma Sharp. In addition to walking, Captain Barclay was active in the financial backing and training of bare-knuckle fighters. The most celebrated fighters that he trained were Tom Molineaux and Tom Cribb, (Champion of England). Captain Barclay's rank was in the 23rd Regiment of Foot, which he joined in 1805. In 1809 he served as aide-de-camp to the Marquess of Huntly on the ill-fated Walcheren Campaign, starting out just 5 days after the completion of the 1000-mile feat. Captain Barclay claimed the Earldom of Airth, his lawyers claiming that this title could be inherited through the female line. The claim was rejected by the House of Lords in 1839. A similar claim to the Earldoms of Menteith and Strathearn was not pursued. A curious aside to the latter claim is that it would have implied that Captain Barclay was the rightful King of Scotland. Captain Barclay died in 1854, as a consequence of injuries from the kick of a horse. The only surviving child from his marriage was a daughter Margaret who had moved to America but eventually re-settled in Great Britain and retired to Cornwall with her eldest son, also a Robert Barclay-Allardice (who later became Mayor of Lostwithiel between 1899-1901 and 1904-6). This Robert Barclay-Allardice married and had one daughter, Mary Graham Barclay-Allardice, whose descendants (through an only daughter, Margaret – the great-great granddaughter of Captain Barclay) live in Gloucestershire and Hampshire. The Lairdship of Ury, heritable only in the male line, passed to a third cousin, Charles Barclay, who lived in Surrey.