In 1803 his son Robert Wallace of Kelly inherited the Kelly Estate, and began major improvements, including a large picture-gallery extension to Kelly House. In 1814 he exchanged his land at North Finnock with Shaw Stewart of Ardgowan to gain the Lower Finnock area adjoining Wemyss Bay, so that his estate boundary on both sides of the road was on a line immediately north of what became Ardgowan Road. He also bought land which he exchanged with the Earl of Eglinton to extend the Kelly Estate across the Kelly Burn into Ayrshire, incorporating the Auchindarroch area of upper Skelmorlie. In 1832 Wallace became Greenock's first MP, and he played a significant part in introduction of the Uniform Penny Post. He had a row of houses built on the west side of the turnpike road between Inverkip and Wemyss Bay, and named the development Forbes Place after his wife's maiden name, Forbes, of Craigievar.