He was one of the gentleman architects who helped define the architectural style that was fashionable after the Restoration.
One of his principal buildings was at Grange Park, Northington which he designed and constructed from 1664 to 1670 for Sir Robert Henley.
The Grange, Northington, was subsequently remodelled by William Wilkins and is one of the earliest Greek Revival houses in Europe.
In 1672, Samwell and William Bruce enlarged and remodeled Ham House, the residence of John Maitland, 1st Duke of Lauderdale and Elizabeth, 2nd Countess of Dysart.
Samwell's designs for the west wing are on display inside Felbrigg Hall today, signed and dated 1674.