Ingamells's career in the arts began in 1959 when he joined
York Art Gallery as an art assistant to the curator Hans Hess, and later joined the art department of the
National Museum of Wales as assistant keeper in 1963. Ingamells published
The Davies Collection of French Art, a catalogue of the National Museum of Wales's French art collection in 1967, and upon its publication returned to York as director of the York Art Gallery. During Ingamells tenure in York he wrote and published articles on the French painter
Philippe Mercier, with Robert Raines, and on the Italian portraitist
Andrea Soldi for the
Walpole Society. Ingamells joined the
Wallace Collection in London as assistant to the collection's director, Terence Hodgkinson, in 1977, before succeeding Hodgkinson as director in 1978. The Wallace Collection did not lend artworks or stage exhibitions in Ingamells initial years as director, and so Ingamell worked on improving the interiors of the museum and revising the Wallace Collection's catalogue. Ingamells joined the
Paul Mellon Centre for Studies in British Art after his retirement in 1992. In 1997 Ingamells published
A Dictionary of British and Irish Travellers in Italy, 1701-1800, a dictionary of more than 6,000 travellers and artists who had embarked on the
Grand Tour. The book arose out of material collected by the art historian Sir Brinsley Ford. He co-edited an edition of the letters of
Joshua Reynolds with
John Edgcumbe that was published in 2000. ==Personal life==