Thomas Edward Cathcart Archer was next to inherit the property. Unlike his father, Thomas had an interest in farming, though in a different style to his great grandfather. He became an orchardist, growing fine apples for distribution locally and on the mainland.

The orchard utilised only a small part of the estate and Thomas continued to lease out the remainder.

The chapel, which had been intended to reform convicts a hundred years before, became an apple-packing store complete with grading machine.

After the Second World War, with returned servicemen hoping for a new life on the land, another wave of disapproval rose against absentee landlords. Although Thomas was in residence and using a small part of the land as an orchard, the Soldier Settlement Scheme reduced Woolmers to about 640 acres, vastly reducing the estate income

Thomas William was the only son of Thomas Edward Cathcart. He continued to maintain Woolmers while occupying himself with history, architecture, building and boating. He did not marry and lived at Woolmers until his death in May 1994.

Thomas bequeathed Woolmers to the Archer Historical Foundation on his death in May 1994 (an incorporated, non-profit organisation). The site was opened to the public in December 1995. Woolmers achieved public museum status in December 1997, which allows for tax-deductible donations. In October 2001 the foundation changed to became the Woolmers Foundation Inc.