John Gully was baptised in St Michael's Church, Bath, England, on 21 March 1819. He was the son of Philip Gully, a porter, and his wife, Mary Vincent. On 22 July 1846 at Melksham, Wiltshire, John Gully married Jane Moore, the daughter of John Eyles. Jane Moore was a widow with one son. She and John Gully were to have six children.
John Gully's formal education finished when he was about 13, and he was apprenticed to Stothert's foundry. He worked in the drawing and design department, where he developed some skill. He had some tuition in painting from a Bristol watercolourist, W. J. Müller, and his first two paintings, an oil and a watercolour, date from about 1835. He finished his apprenticeship about this time and joined the staff of the Bath Savings Bank. In 1846 he left the bank to become an accountant in his father's ironmongery business.
In 1851 a business or family crisis of some kind induced John Gully and his family to emigrate. Gully had read about New Zealand in Charles Hursthouse's account of the settlement of New Plymouth. The family left London on 23 December 1851 on the John Phillips and arrived at Auckland on 5 April 1852. After a month there the ship proceeded to New Plymouth, where passengers were landed on the beach by Moturoa on 9 May.
Gully was described as slender, a little over average height, and very dark, with dark hair and brown eyes. He was alert and active, with a genial manner. He took up land at Ōmatā but was not suited to the farming life. In 1854 he acquired the Ōmatā store but found that there were not enough settlers to support it. From 1856 he was in financial difficulties, and in 1858 bankruptcy forced him to move into New Plymouth, where he did casual clerical work. In 1860 he was briefly in the militia but was invalided out. On 31 July 1860 he and his family left New Plymouth for Nelson on the Airedale.
While in New Plymouth Gully had continued to draw and paint. He sketched Mt Taranaki and its environs and depicted local scenes and houses. He was secretary of the Taranaki Institute from 1858 to 1859 and probably in that connection met Julius Haast, who became his friend and patron. Gully's friendship with J. C. Richmond also dates from his sojourn in New Plymouth.
In Nelson, Gully became drawing master at Nelson College from 1861 to 1863. During this period he sketched in the Nelson Lakes area and painted local scenes. More importantly, he produced 12 watercolour paintings of South Island mountains and glaciers from sketches by Julius Haast. This set of paintings was used to illustrate Haast's lecture on the mountains and glaciers of the Canterbury province, which was read to the Royal Geographical Society in London on 8 February 1864.
On 8 August 1863 Gully began work as a draughtsman at the Nelson provincial survey office. He travelled for the office and in January 1865 was one of the survivors of the capsize of the Wallaby's lifeboat on the bar of the Buller River, when the Nelson superintendent, J. P. Robinson, and three others were drowned. In 1874 Gully became chief draughtsman at the survey office. He retired from full-time work in 1877.
Gully exhibited at the New Zealand Exhibition in Dunedin in 1865, showing work on behalf of the survey office and on his own account. He gained a silver medal and sold all the paintings he exhibited. This recognition placed his name at the forefront of New Zealand watercolourists. His reputation was further enhanced by his exhibits at the Nelson Institute Exhibition in February 1866. The paintings included scenes of the town of Nelson, the Kaikōura Mountains, Mt Cook (from sketches by John Rochfort), and the West Coast. Some of the paintings went on to the Intercolonial Exhibition of Australasia in Melbourne in 1866–67. Two paintings sold for £60 each and Gully made arrangements for agents to sell his work in Melbourne. He began an association with the Victoria Academy of Arts and was represented at many of its exhibitions. In 1873 he visited Victoria briefly and praised the people as his first real patrons.
Gully also sent paintings to London. A painting of Mt Cook and the Southern Alps was accepted by the Royal Academy in 1871, and a number of his paintings were sold. He also sent nine paintings to the New Zealand court at the 1873 International Industrial Exhibition in Vienna.
In September 1874 the governor, Sir James Fergusson, invited Gully to accompany him on a voyage round the western and southern coasts of the South Island. The sketches Gully made show his complete mastery of the pencil, and many fine paintings, especially seascapes and views of the southern sounds, resulted from the tour. Gully's diary of the trip shows his enjoyment of genial company, good food and wine, pleasant music, and whist.
In 1875 Gully became a foundation member of the Otago Art Society. He was in communication with William Hodgkins and exhibited at most of the society's exhibitions. After his retirement Gully went south in March 1877 to sketch at Wānaka, Milford Sound, Wakatipu and Manapōuri. He later used these sketches extensively as a basis for paintings.
In 1865 there had been an unsuccessful attempt to publish a portfolio of his paintings of New Zealand. In 1877 the project finally came to fruition with the publication in Dunedin and London of New Zealand scenery. The 15 chromolithographs based on Gully's original watercolours were accompanied by descriptive text written by Haast. The plates depict prominent landmarks and scenes, from Mt Taranaki and Lake Taupō in the north to Bradshaw Sound in the south. Gully was disappointed with the reproductions, which are gaudy by comparison with the light and airy originals.
In retirement Gully exhibited in Nelson, Wellington, Christchurch, Dunedin, Melbourne, Sydney and London. At the Sydney International Exhibition in 1879 his landscapes received an award. His exhibits at the 1880 International Exhibition in Melbourne showed a variety of scenes in the Southern Alps and lakes, and one in Victoria. In 1885 at the New Zealand Industrial Exhibition in Wellington he was awarded the first prize for watercolour painting. He also exhibited eight paintings at the Colonial and Indian Exhibition in London in May 1886.
In 1880 Gully had visited Victoria again. He had also visited his daughter in the Hutt Valley in 1879 and sketched and painted in the Wellington area. His last major sketching trip was to Mt Cook and the southern lakes with J. C. Richmond in 1887. He was active in the Nelson Horticultural Society and the Nelson Institute, and was president of the Nelson Harmonic Society during 1883 and 1884. In 1885 he reported to the governors of Nelson College on the teaching of drawing in the school, and recommended its encouragement in the interests of the national standard of design and presentation of manufactures. In 1883 Bishop A. B. Suter raised again the suggestion that Nelson should have an art gallery. An 1876 proposal that the city acquire one of Gully's paintings was revived, but it was not until 1899 that his view of the western coast of Tasman Bay, which had won first prize at the 1885 Wellington exhibition and was shown in London in 1886, was purchased by public subscription. The Bishop Suter Art Gallery in Nelson now has the largest public collection of Gully's paintings. John Gully died in Nelson on 1 November 1888.
Gully was an assiduous sketcher, often using colour washes or writing down the colours to be used in the finished painting. He also painted from sketches by others, and from photographs. He painted very few oils, but has left some 900 watercolours on smooth paper, often mounted on linen. He was happiest depicting landscapes and seascapes, although many of his pictures include figures, animals, or buildings, to add interest and give a sense of scale.
During his lifetime, and for many years after, his paintings were highly regarded for their technical excellence and faithful portrayal of New Zealand scenery. However, later there was a reaction and a reassessment of Gully's place in New Zealand art, where he was said to have produced a distorted representation of the southern hemisphere through the limited vision of his English background and training. The return to New Zealand in 1974 of the 12 paintings done for Haast's 1864 London lecture provided an opportunity for re-evaluation. These paintings, together with the best of his other work, place Gully as a leading watercolourist, who was inspired by the scenery of the country of his choice. Gully painted what appealed to him, and to his audience. His work retains its popular appeal.