By 1844 there was plenty of business but little architecture. Mason dissolved his partnership with Paton and took up farming in Epsom. He designed a windmill there and may have had some hand in the building of St John's College at Epsom, but these were architecturally unproductive years. He continued farming in various places around Auckland and entered public life. In 1851 he was elected to the Common Council of Auckland, but eventually a substantial commission turned up. Mason was living at Howick late in 1854 when he was appointed architect of the 10,000 pound project to build a new Government House. The result was a large, two-story, neo-classical building, whose manner may not have been entirely of Mason's choosing. It is made of timber treated to look like stone. Its principal facade has a central breakfront with round-headed windows in the upper floor. It has been the subject of rather mixed reviews since its completion in 1856 but it is a substantial house for New Zealand at the time and of its nature a significant building.