He learned the use of oils and watercolour, and executed perspective drawings for Sir George Gilbert Scott.

While articled to H. R. Newton, he attended classes at the Architectural Association and at the Royal Academy of Arts, winning the Pugin travelling scholarship in 1871.

[5] The Sir John Sulman Prize for "the best subject/genre painting and/or murals/mural project executed during the two years preceding the [closing] date ..." has been held at the Art Gallery of New South Wales since 1936.

When initiated the prize was about £100 annually and for the best subject painting or mural decoration by artists resident in Australia.

Sulman also endowed a lectureship in aeronautics at the University of Sydney in memory of his son Geoffrey who was killed during World War I while serving with the Flying Corps.

John Sulman's extensive collection of diaries, sketchbooks, correspondence, manuscripts, drawings and photographs was in the possession of family members for many years, but in 2018 it was lodged and catalogued in the State Library of New South Wales, Sydney.

The papers reveal Sulman as a true polymath: architect, artist, author, educator, town planner, politician, historian, statesman, patriot, commentator, benefactor and polemicist.

Sulman married Sarah Clark Redgate on 15 April 1875 at the Congregational Church at Caterham, Surrey.

They had three children, a son Arthur (1882–1971) and daughters Florence E. (1876–1965) and Edith (1877–1907)[6] They moved to Sydney, Australia on account of his wife's tuberculosis.

[7] His parents John (senior) and Martha moved into Addiscombe at Lane Cove Road, Turramurra.

When they returned, he turned the cottage he had originally intended for his parents at Boomerang Street, Turramurra into their family home Ingleholme, which developed into a "rambling complex of gables, bays, turrets and chimneys".

In 1913 John Sulman purchased the magnificent property "Kihilla" at Lawson in the Blue Mountains as a second home; it remained in the family until 1953.

[14] Mrs Sulman was socially active, being a prominent member of such organisations as the Leura and Lawson branches of the Red Cross Society.

[18] Sulman retired in 1928[19] but remained a highly visible presence in civic, art and architectural circles, taking a prominent role in many public debates.