A father condemned as a leading Royalist soldier and his son condemned as a plotter against king the Protestant Charles II and his brother James, who was to become England's last Roman Catholic monarch to reign over the three kingdoms (England, Ireland,& Scotland (Wales is a Principality - Incorporated int England under "Laws in Wales Acts 1535 and 1542" by Henry V111)). In 1683 he was crowned James II of England & Ireland, and James VII of Scotland. His reign ended with the "Glorious Revolution" (1688).
The backdrop to the commisioning, and building of Little Cassiobury was the Civil War, Regicide, Parliamentary Comonwealth, Restoration, and the "Exclusion Crisis".
Its not clear which Arthur commisioned Little Cassiobury or for whom. Whose widow was its first resident is not clear either.