 The late 20th century saw a number of exhibitions toured around the country and new studies of his work.In 1945, the Hocken Library held an exhibition of drawings and paintings by O'Brien and Lily Daff.John Harris of the Otago University Library wrote in the catalogue that O'Brien's 'combination of skilled draughtsmanship and genuine feeling for the pattern and colour of our hills and bush and harbour give [his works] historical as well as artistic significance'.