Brill (née Clarke), who had a flair for flower paintings, married fellow artist Reginald Brill in 1925 and served as his primary model for much of their early relationship. The pair spent two years at the British School at Rome from 1927-29. Later in life they took over as wardens at The Little Hall in Lavenham, Suffolk, which was a hostel for artists from Kingston School of Art where her husband had been headmaster.
The picture, which is available for £1000, is one of more than 100 works by women artists in the current show. Winifred Knights, Evelyn Dunbar and Clare Leighton are among those represented.
Founded by Anthony Liss in 2017, Modern British Art Gallery offers an online-only selection of 20th century British pictures priced £100-10,000.
It celebrates lesser-known artists from the period, and has sold to institutions such as The British Museum, The National Portrait Gallery and The Imperial War Museum.