On his return Robert Adam set up a practice in London, with his brother James. He was elected a member of the Royal Society of Arts in 1758, and the Society of Antiquaries in 1761. He served as Member of Parliament for Clackmannanshire & Kinross-shire from 1768-74.
The 6th Earl of Coventry brought Robert Adam to Croome in 1760. His first garden buildings were the Temple Greenhouse, built from Painswick Limestone, in 1760-63, and the interior of St Mary Magdalene Church.
Although initially an architect, Adam was keen to assert his influence on the interior of buildings, and this he did at Croome. The Earl employed him to furnish most of the rooms in his London House in Piccadilly and three of the rooms inside Croome Court. The Long Gallery was possibly his first total room design.