Booth, Sir Henry William Gore- (1843–1900), 5th baronet, landlord, and Arctic explorer, was born at Lissadell House, Co. Sligo, second son among two sons and three daughters of Sir Robert Gore-Booth, 4th baronet, landlord, and MP for Sligo, and his second wife, Caroline Susan (née Goold). Henry succeeded to the title and the family estate on the death of his father (1876), owing to the death of his brother Robert (1861) as a result of a boating accident in Sligo Bay. Educated at Eton, he participated in three private sailing, fishing, and shooting voyages to Norway with Arthur Macmorrough Kavanagh (qv) in 1864–6 before taking over the management of the estate at the age of 23 following the death of his father's agent. He managed a good system of accounts, developed a reputation as a popular and benevolent landlord, and was high sheriff of Sligo in 1872. He invested most of his time in the development of the estate, his tenants, and local institutions. By 1879 he had most of his rents reduced to the Griffith's valuation figure – this before the Irish National Land League had started to campaign for it. He was chairman of the Sligo, Leitrim and Northern Countries Railway. After his death a steam engine was named Sir Henry in commemoration. He was also a partner in a mine operation at Gleniff, which provided employment to many of his tenants.
Sir Henry participated in two significant privately organised and funded expeditions to the Russian Arctic. The first was in 1879 with Lars Jorgensen and Capt. A. H. Markham, RN, in the chartered cutter Isbjorn, making extensive exploration of the shores of Novaya Zemlya and passing through Matochkin Shar to the Kara Sea. The objectives of the expedition were sport hunting and fishing, surveying the coast, observing the drift of the ice flow, and collecting natural history specimens. They reached their highest latitude of 78° 24’ N south of Franz Josef Land.
Sir Henry's next Arctic adventure was in search of his missing sailing acquaintance Mr Leigh Smith and the crew of Smith's privately owned exploring ship the Eira, which sank off the shores of Franz Josef Land in 1881. Sir Henry purchased and fitted out for the Arctic a 50-ton ketch named Kara, with which he joined a search party that included two other vessels, the Hope and Willem Barents, in May 1882 to seek and find Smith. The Eira crew survived the winter of 1881–2 in a cabin built from natural materials and the salvaged timbers and sails of the abandoned ship. In 1882 Smith and his crew reached Matochkin Shar in the ship's lifeboats, where they met with the three searching vessels including the Kara.
In 1884 Sir Henry made another voyage to fish for whale off the coast of Jan Mayen Island and the east coast of Greenland. He was accompanied on most of his sailing voyages by his sailing butler and personal servant, Thomas Kilgallon, who had become his valet at the age of eleven and served Sir Henry and his family for over seventy years. In 1886 Sir Henry took the examination for his Board of Trade sailing-master certificate, which he obtained. He made his last trip to northern waters in 1892, sailing again off the coast of Greenland. Sir Henry died 13 January 1900, while holidaying at St Moritz, Switzerland, following an attack of influenza. He is buried in Lissadell churchyard with his wife, whom he predeceased by twenty-seven years.
He married (1867) Georgina Mary Hill of Tickhill Castle, Yorkshire. They had five children: Constance (qv) (Markievicz), Josslyn, Eva (qv), Mabel, and Mordaunt. Josslyn (1869–1944), the eldest son, who became the 6th baronet, was active in the Irish co-operative movement and a noted cattle breeder. One of Henry's grandsons, Paul (1909–84), eldest son of Mordaunt, became a diplomat, whose missions included being the senior figure resident at the British embassy in Tokyo in 1941 when he received Japan's declaration of war. He was appointed ambassador to Burma in 1953, and served as permanent under-secretary at the Foreign Office 1965–8 and head of the diplomatic service 1968–9, when he retired and was made a life peer.