Lecky, Squire Thornton Stratford (1838–1902), master mariner, cartographer, and writer on navigation, was born in Downpatrick, Co. Down, fifth son of Holland Lecky of Castle Lecky, Magilligan, Co. Londonderry, and Ballyholland House, Co. Down, and his wife Elizabeth, daughter of the Rev. Thomas Daniel of Co. Londonderry. His family claimed descent from Malcolm de Lecky, lord of Lecky in Stirlingshire, Scotland. Educated at Gracehill, Co. Antrim, he went to sea in 1852 against the wishes of his parents, joining the Alfred as a midshipman. On his return from a trip to Calcutta he indentured himself to James Beazley, a Liverpool shipowner, and initially served aboard a clipper ship, the Prince Arthur. In early 1857 he was appointed second mate of Star of the East, a China clipper, and carried out several voyages to the east. Due to differences with some of the senior officers of the Beazley Line, he transferred to an American-owned ship, the Jacob A. Westerfeldt, and then joined the East India Company navy. He served as a second master for two years aboard the Indus, Frere, and Napier until this force was disbanded at the end of 1858.
He then served aboard a series of ships, including the Nell Gwynn of Bristol and the Waterford-registered Uruguay, carrying out voyages to North and South America. During the American civil war he served aboard a confederate blockade-runner, the Bahama, and took part in an unsuccessful attempt to run the blockade at Charleston. In 1864 he received his master's certificate and subsequently served aboard ships of the Inman Company and of Messrs Lamport & Holt. In 1865 he joined the Pacific Steam Navigation Company and began a series of voyages that took him to the Atlantic and Pacific coasts of South America. He had a keen interest in marine survey and cartography and began to carry out surveys during these voyages, sending information to the British admiralty and recommending changes to the charts covering areas such as the Straits of Magellan and the Gulf of Peñas. In 1865 he detected a submerged rock pillar off Rio de Janeiro, which was subsequently christened the ‘Lecky Rock’ on admiralty charts. He later discovered a submerged rock pillar off the River Plate and the ‘Lecky Bank’ to the north-east of the river's entrance. The admiralty were, of course, delighted at having such hydrographic surveys carried at no expense, and published his navigational aids for the channels around Port Tongoy in Chile, Punta Arenas, and Cape Pillar.
In 1876 he left the Pacific Steam Navigation Company and initially worked as a boatswain on board the City of Mecca. Appointed as commodore of the British steamers of the American Line in 1878, he served in the capacity of an officer of the Royal Naval Reserve in the Egyptian campaign of 1882. Commanding the transport ship British Prince, he volunteered to bring supplies to the front and was awarded the Egypt Campaign Medal and the Khedive's Star. In 1884 he was appointed marine superintendent of the Great Western Railway, a post he held until 1898, when bad health forced him to retire. The GWR retained him in an advisory capacity until 1900, when his failing health forced him to retire completely. Diagnosed as having a severe form of pharyngitis, he underwent thirty-seven operations in the course of three months. He died 23 November 1902 at Las Palmas, and was buried in the English cemetery. He was married twice and was survived by two sons and one daughter. His son Halton Stirling Lecky, RN, later of the Royal Indian Navy, published The king's ships (2 vols, 1913).
Apart from his navigational guides, published by the admiralty, he published Wrinkles in practical navigation (1881). This important publication had run to ten editions by the time of his death and remained a standard text in nautical colleges for many years. He also published The danger angle and off-shore distance (1892) and Lecky's A. B. C and D tables (1892). A member of the Royal Astronomical Society and the Royal Geographical Society, he was also a leading member of the Mercantile Marine Association.