With an interest in sports, he promoted boat racing, boxing and wrestling among the workmen. In 1872, he married Amy Hewison, the daughter of a corn merchant, and they moved into 6 Windsor Terrace, Jesmond, Newcastle. They would have six children, including the painter and illustrator, Millicent Sowerby, and the writer, Githa Sowerby. Githa collaborated with Millicent, but is now best remembered for the semi- autobiographical play, Rutherford and Son (1912), which rehearses some of the tensions within her family, including her father’s apparent desire to break free of the responsibilities of the family firm.

Despite the implications of his daughter Githa’s play, John Sowerby did make several creative innovations in the 1870s that initially boosted sales. These included adapting Arts and Crafts designs for glassware, registering a peacock’s head as the firm’s trademark (1876) and introducing vitro-porcelain (1877). At the time that the Ellison Glass Works became a limited company, in 1882, it covered five and a half acres, and employed about 1000 workers, making it one of the world’s largest mass-producers of glass.

The death of his father in 1879 probably allowed Sowerby greater artistic freedom and, from that date, he began to exhibit paintings of landscapes and gardens, at the Royal Academy, and illustrate children’s books. His early books included Afternoon Tea (1880, with H H Emmerson), At Home (1881, with Thomas Crane) and At Home Again (1883, with Thomas Crane and Eliza Keary). Though his first illustrations were considered derivative of Kate Greenaway, he soon established his own distinctive style. In becoming an artist and illustrator, with a special interest in flowers, he followed in the footsteps of several generations of Sowerbys, many of whom were naturalists, including botanical illustrators.

By the early 1880s, the Ellison Glass Works was achieving record sales, and Sowerby and his family were living in comfort at Ravenshill, Gateshead, and Washington Hall. However, he soon began to lose significant amounts of money, and the board of directors forced him to resign. In 1884, he was declared bankrupt and living in furnished lodgings at 3 North Terrace, Whitby, Yorkshire. Despite this nadir in his fortunes, the firm survived, even flourished, and he returned as a salaried worker. By 1891, he and his family were living at Field house, High Team, Gateshead, and his eldest son, (John) Lawrence, had become a ‘Glass House Manager’. With less responsibility, he returned to the production of children’s books: Jimmy: Scenes from the Life of a Black Doll (1888), Young Maids and Old China (1888, with F W Bourdillon) and Rooks and their Neighbours (1895).

In 1896, the Sowerbys sold the Ellison Glass Works. (once bought, it remained a going concern until 1972). By that date, John’s younger brother, Charles, had migrated to the United States, and John’s son, Lawrence, had left the factory refusing to return. The family was living at Chollerton house, Wall-on- Tyne, about 25 miles west of Gateshead, and it was there that John’s mother, Anne, died in 1897.

From the end of the 1890s, Sowerby moved frequently, and exhibited from various addresses, so enabling himself to experience and respond to a variety of landscapes. Between 1898 and 1901, he, his wife and daughters lived at Boxted House, Essex. Then, in 1901-2, he was in the Carlisle area, staying with members of the wider Sowerby family, at Williamstone Farm, Slaggyford, and, further west, with his son, Lawrence, who had become a farmer, at Round Hill, Sebergham, Wigton. (Lawrence married later the same year, and migrated to Canada in 1912.) By 1904, Sowerby was living in Sutton Courtenay, near Abingdon (then in Berkshire and now in Oxfordshire). In spring 1909, he held a solo show at the Baillie Gallery, London, entitled ‘Cottages and their Gardens’.

Sowerby and his wife retired to Orde house, Whitchurch, Herefordshire, by 1910, and he died in the county on 14 December 1914.