Among the UK’s best-known 20th century painters, Seago is widely collected. He was patronised by the royal family and was one of the artists appointed to paint the Queen’s Coronation.
His landscapes are particularly popular and include scenes of his native land as well as the wider world.
The oil on canvas of Windsor here measures 2ft 2in x 3ft (66 x 91cm) and is offered for £110,000.
The show coincides with the gallery’s exhibition of London scenes by contemporary painter Ken Howard.