 Douglas's most important patrons were the Grosvenor family of Eaton Hall, Cheshire.In 1865 he was commissioned to design the entrance lodge and other structures for Grosvenor Park in Chester, and St John's Church in the village of Aldford in the Eaton Hall estate for Richard Grosvenor, 2nd Marquess of Westminster.When the marquess died in 1869 he was succeeded by his son Hugh Grosvenor, 1st Duke of Westminster.