In between his Parliamentary work, Coke and his wife had been maintaining and improving his estates since they took possession of it in April 1776. The cornerstone was Holkham House, a "temple to the arts" built by Coke's great uncle. Knowing that he did not have the same understanding of classical architecture and art, Coke mainly left it alone, instead focusing on the park and gardens. The grounds had been laid out during the 1720s and 1730s, in a design which quickly became seen as old-fashioned. Coke had the lake massively expanded, shifting a total of 36,000 cubic yards of earth, and employed the gardener John Sandys from 1781. Sandys created several large pieces of woodland, planting over 7,000 trees in 22 acres near the Eastern Lodge, another ten acres near the lake, and four acres on marshland. In 1784 a further woodland expansion was undertaken, with 40 acres and 11,000 trees, and between 1785 and 1789 396,750 trees were planted on a further 179 acres. He retired in 1805 and was replaced a year later by James Loose, but continued to advise Coke on forestry matters. The library was also expanded, through the work of William Roscoe, who bought books including the "Mainz Psalter" for Coke between 1814 and 1842.