Frederick George Gurnsey was born in Newport, Monmouthshire, Wales, on 18 January 1868, one of eight children of Anna Maria Griffin and her husband, Henry William Gurnsey, a tin plate worker. His childhood was largely spent at Westbury Leigh, Wiltshire. The vicar of nearby Frome, Somerset, encouraged him to study carving. Apprenticeship and employment followed with Harry Hems and Company, a leading ecclesiastical carving firm in Exeter. On 23 May 1893 Gurnsey married Rose Ellen Burgess at Frome.
Gurnsey's carving commissions entailed frequent absences from home. In 1900 he inherited the running of an antique shop in Bristol and in 1903 the Gurnseys moved with the business to Glastonbury, where Frederick also operated as a modeller and carver. Ill health led him to visit New Zealand in 1904–5. In Wellington he met E. C. Isaac, chief inspector of technical schools, and renewed his acquaintance with Robert Herdman-Smith, a teacher at Wellington Technical School whom he had known in England. Returning to Britain, he undertook brief training at art schools in Edinburgh and London, and was employed to execute architectural carvings for the headquarters of the Norwich Union Life Insurance Society in Norwich. By 1906 he was teaching at the Norwich School of Art.
In July 1906 Gurnsey was appointed to replace Charles Kidson as an instructor at the Canterbury College School of Art in Christchurch, New Zealand, where Herdman-Smith was now director. He, his wife and two sons arrived in Lyttelton in January 1907. He taught carving, modelling, casting, enamelling and metalwork, was the school's acting director from September 1917 to April 1920. From 1911 to 1920 he was a member of the council of the Canterbury Society of Arts. On his resignation in 1923 to pursue full-time carving, the Canterbury College annual report acknowledged 'the high place accorded throughout New Zealand, to the Craftwork of students trained in the School under him'. These included the sculptors William Trethewey and Ronald Ranby. Another protégée was Kathleen Browne: Gurnsey secured her a teaching position at the school and employed her on ornamental carving commissions.
Gurnsey shared Auguste Rodin's view that inspiration comes only by understanding the beautiful, through slow progress and patience. He executed hundreds of wood and stone carvings, primarily for churches but also for civic buildings, public monuments and private commissions. His carving is notable for architectural precision, balanced application of ornament, sensitivity to location and, occasionally, wit and charm. A genuinely New Zealand idiom is seen in the tuataras on the prayer-desk at St Andrew's Anglican Church, Maheno (1938), and Gurnsey's ubiquitous angels range from the robust neo-Baroque heads on the font cover of Bishopscourt Chapel, Christchurch (1926) to the art nouveau elegance of its counterpart at the Church of St Thomas, Woodbury (1938). His signature, the Tudor rose, alluded to his wife's name.
Gurnsey's best-known works are the Christchurch cathedral reredos, and carvings and furnishings in the cathedral's Chapel of St Michael and St George (1932–51). Other major works include carvings for the Bridge of Remembrance in Christchurch (1924), the Massey Memorial in Wellington (1930), the Church of the Good Shepherd, Tekapo (1935), St Mary's Church, Timaru (1925–47), and All Saints' Church, Palmerston North (1950).
Equally confident whether working in wood or stone, Gurnsey displayed remarkable stylistic versatility, reflecting the technical prowess of a craftsman more than the self-consciousness of an artist. He was less successful when handling imaginative, pictorial reliefs, such as the Canterbury Pioneer Women's Memorial on the Bridle Path near Lyttelton (1940). His longtime assistant, Jake Vivian, recalled Gurnsey's pleasure in carving armorial bearings at Government House in Wellington. In addition, Gurnsey executed repoussé church plate, and during the depression he diversified into domestic furniture. He refused to rush his work and treated a breadboard as seriously as an altarpiece.
Gurnsey's interests included golf, bridge, music (he was a fine tenor) and religion. His spiritual curiosity led him to attend Anglican, Catholic and Presbyterian church services but ultimately he endorsed theosophical beliefs. He was a perfectionist in his work and possessed considerable charm and a mischievous, whimsical wit. He died at Christchurch on 23 October 1953, survived by his wife and two sons. Because of his personal reticence about his talent, and the status of carving – on the boundaries of craft and art – his considerable achievements have been neglected.