George Alexander Troup was born on 25 October 1863 in London, England, the son of Scottish parents Jane Gildawie and her husband, George Troup, a provision warehouseman and cabinet-maker. The fifth of nine children and the eldest son, he grew up in Edinburgh, where he attended church and Sunday school, and had Bible lessons at home. When George was 10 years old his father died; from necessity, his mother and sisters worked as seamstresses.
In 1874 George Troup won a place at the prestigious Robert Gordon's College in Aberdeen. In 1879 he took up an apprenticeship with C. E. Calvert of Edinburgh, a licensed engineer, surveyor and architect. He also attended night classes in art and architecture at the Royal Institute, where he won a number of major prizes.
Troup completed his apprenticeship in 1882, and shortly afterwards his mother died. In December 1883 he sailed from London for New Zealand on the Fenstanton. On arrival Troup worked with the Survey Department in Otago. In 1886, having studied at the University of Otago School of Mines, he commenced a 39-year career with New Zealand Railways, initially as a draughtsman with the district engineer's office in Dunedin.
At this time Troup became involved with the Presbyterian church and was influenced by Rutherford Waddell. In April 1888 he moved to Wellington to work at the head office of New Zealand Railways, and began a long-term connection with St John's Presbyterian Church in Willis Street. Here he developed the concept of the young men's Bible class, which he had discovered when attending Regent Square Presbyterian Church in London.
On 3 March 1897 at Wellington George Troup married Annie Mary Sloan; they were to have four children. Troup worked his way up through the New Zealand Railway Department and in 1919 became officer in charge of the architectural branch. He instituted a programme for training engineering cadets, and was involved in many major projects for the completion of the North Island main trunk line. He also planned new stations at Oamaru and Wanganui and designed the Dunedin railway station (1904). In addition, he designed the Wellington railway offices (1903) and in 1910 made preliminary sketches for the Wellington railway station, which was eventually designed by William Gray Young. His station buildings are now regarded as a valuable part of the architectural inheritance. He received third prize in a competition in 1911 for the design of the new Parliament Buildings. In 1907 he was elected a fellow of the Royal Institute of British Architects.
In 1903 Troup became founding president of the Bible Class Union within the Presbyterian church. He was also instrumental in founding the Wellington Boys' Institute which opened in 1893. This was initially a Sunday school for underprivileged boys, but was taken over by the Bible class of St John's Presbyterian Church and developed into an organisation providing sports, music and educational opportunities for young men.
In the 1890s Troup acquired tennis courts and swimming pools, primarily for the use of the young men's Bible class and the Boys' Institute, and a bush reserve adjacent to the Karori Waterworks for public use. He was a prime mover and shareholder in the Kelburne and Karori Tramway Company. In 1905 he purchased 365 acres of land at Plimmerton for his personal use, and ill health led him to take up his interest in cattle breeding on the property. He ran the Cluny Holstein–Friesian farm between 1908 and 1923 and was president of the New Zealand Holstein–Friesian Association during that period.
George Troup retired from the railways in 1925 and that year was elected to the Wellington City Council. He became chairman of the Works Committee, and was responsible for the establishment of a milk treatment station, the airport at Rongotai and a second tunnel through Mt Victoria. In 1927 he was elected mayor and was involved in raising money for the construction of the National Art Gallery and Dominion Museum building, the War Memorial Carillon and the new railway station in Wellington (which he had designed in 1910). He retired in 1931 after an election defeat.
Troup was deeply involved in education, serving on the boards of governors of several schools. For 21 years he was chairman of the British and Foreign Bible Society in New Zealand. He was also active in the arts, charity and other community organisations. In 1931 he was appointed a CMG and in 1937 a Knight Bachelor.
George Troup's involvement with the Presbyterian church was the inspiration for his breadth of public interests and commitment to the development of Wellington city. He had a forceful personality and 'the most direct of speech' for those he considered to be undeserving. Ill health plagued him for many years and he died at his Kelburn home on 4 October 1941 aged 77. He was survived by his wife and four children.