The 40-plus lots come for sale on September 21 from the daughter of the Southall builder Samuel LM Avery. It was when clearing her home in Egham, Surrey, that her children discovered the items wrapped in newspaper dated 1971.
Samuel Avery visited the Martins regularly in their place of work both professionally and socially.
Family lore has it that the sometimes chaotic nature of the brothers’ finances meant many purchases were made directly from the studio rather than from the family shop in Holborn.
Avery’s original collection of Martinware included the fountain which he donated to the borough of Southall following Robert Wallace Martin’s death (later erected in the Manor House Grounds), and other important pieces lent to various exhibitions in the first half of the 20th century. He also supported Clement Martin (son of Wallace) in the late 1920s when an unsuccessful attempt was made to revive the works.
Alongside a series of vases and gourds, the collection includes nine face mugs of different sizes (variously estimated from £800-1200 up to £4000-6000) and an 8in (20cm) high triple bird group dated 1904 (£25,000-35,000).
A series of architectural elements and terracotta plaques were probably produced by Robert Wallace Martin prior to him setting up the family business.