Brothers William Joseph Wadham (1863–1950) and Alfred Sinclair Wadham (1866–1938) were English painters in watercolors who were active in Australia in the late 19th century. The younger brother invariably used the name Alfred Sinclair.
Wadham and Sinclair were sons of Benjamin Brassett (or Braffat) Wadham (1816–1904), a painter of some note who was deaf and dumb from birth. Joseph learnt to paint at his father's side, and accompanied him on his many sketching trips throughout England and Wales, and had the privilege of seeing many of England's premier artists at work. Joseph had his first picture accepted for exhibition by the Walker Art Gallery, Liverpool, at age 14. In 1885 he left for Australia.
Alfred studied at the Liverpool Academy of Arts and left for Melbourne, Australia, in 1887, to join his brother, who had made the journey a year earlier. After a brief stay they moved to Adelaide, where they joined the South Australian Society of Arts, and in 1892 were founding members of the Adelaide Easel Club, with Joseph the first president. They had exhibitions in Melbourne in 1889 and 1895, which were favourably and extensively reviewed.
They set up a gallery "Wadham & Sinclair's Fine Art Institute" on Grenfell Street where they showed their works and ran art classes. They made an extended visit to Mount Gambier in mid-1888. In 1891 they moved their studio to Mutual Chambers, King William Street, and had several art classes running.
In 1892 they were elected to the Adelaide Art Circle, whose president was H. P. Gill, and the South Australian Society of Arts, but were among those (like G. A. Reynolds and A. Scott Broad) who later in the year resigned to form the Adelaide Easel Club.
They had a sketching holiday in New Zealand in 1896, and on their return moved their studio to new premises in the Widows Funds Building, Grenfell Street. Joseph Wadham took an exhibition to Perth in 1896 and 1897, touring the goldfields and making further sketches. A major exhibition in 1897, opened by the Governor, featured several paintings of Kalggorli and Perth; among the works shown was a joint effort – Precipice Gorge, New Zealand, painted in oils. Shortly after this exhibition, Alfred returned to England.