Armstrong held his first solo exhibition in 1928 at the Leicester Galleries in London. In 1933 he joined Unit One and displayed a set of semi-abstract paintings at their one, extended, exhibition. Throughout the 1930s Armstrong continued to work as a designer as he also continued to develop his art. He produced a number of remarkable posters for Shell and also produced four posters for the General Post Office.Armstrong designed a number of book covers for the Hogarth Press, including for William Plomer's Sado published in 1931. He worked on the first production of the ballet Façade] and on a number of Alexander Korda's film productions, designing costumes for The Private Life of Henry VIII, Rembrandt and I Claudius.
Newlands Corner is a 103-hectare (250-acre) nature reserve east of Guildford in Surrey. It is owned by the Albury Estate managed by the Surrey Wildlife Trust under an access agreement between the estate and Surrey County Council.