The artist Eppo Doeve painting the Martineau children at “Old Lodge in Terlow (Buckinghamshire),” Great Britain, July 1954, by Willem van de Poll, via Nationaal Archief (Netherlands).
I have not been able to find out anything about these siblings or the home. I cannot find an Old Lodge in Terlow, Buckinghamshire, or indeed a Terlow anywhere in Great Britain. The Martineau family is quite important in Birmingham (an ancestor of the Duchess of Cambridge was a Martineau), but apparently not in Buckinghamshire. Perhaps the photographer made some mistake in his notes.
The son on the right seems to have three golf balls between his fingers. A young amateur champion?
Three women in the garden; the one on the right is probably the mother of the photographer, Aalst, Gelderland, the Netherlands, undated, by Willem van de Poll, via Nationaal Archief (Netherlands).
“Hilde Eschen (right) with two women in the garden of Weikersheim Castle,” Baden-Württemberg, Germany, July 1959, by Willem van de Poll, via Nationaal Archief (Netherlands).
Eschen was the photographer’s wife.