Artist, art collector and dealer. Born in Edinburgh, the son of a dentist and surgeon, Orrock studied medicine at the University of Edinburgh and moved to Nottingham to practice as a dentist. He later settled in London.
Orrock studied painting under William Leighton Leitch (1804-83) and Thomas Stuart Smith (1815-69). He was noted as a watercolourist and for his landscapes, exhibiting works at the Royal Scottish Academy and Royal Academy. Orrock was also responsible for copying the style of others, and altering or 'improving' works by the likes of John Constable before selling them on to collectors like as John Ruskin (1819 - 1900) and William Lever, Viscount Leverhulme (1851 - 1925).
Orrock was a dedicated connoisseur of contemporary British art and emulated several of those artists in his own work. He was a particular enthusiast for the works of J. M. W. Turner (1775 - 1851), owning some of his most important works. He was also an enthusiastic collector of oriental ceramics and Adam-style furniture.
He died in Middlesex. His paintings today are held by various galleries, including the Victoria and Albert Museum and Nottingham City Museums and Galleries. His work Stirling from Cambuskenneth in the Smith Art Gallery & Museum in Stirling. Leverhulme bought Orrock's collection on his death and much was used to form the core of the Lady Lever Art Gallery at Port Sunlight on the Wirral.
