Orde demolished the modest old Campbell house and replaced it with a grand Gothic-revival mansion designed by architect Joseph Gordon Davis and completed in c. 1830.

The core of the older house was retained, but was extended into an L-shaped plan, with new exterior and interior decoration, and a large octagonal tower at the south-west corner.

Orde also greatly expanded and improved the grounds and estate, engaging William Hooker to extend the gardens in 1830.

[4] In March 1949 an announcement was made that it would open in June as a national holiday centre for young people.

In 1995 local government was reorganised again, although Kilmory remained in use as the headquarters of the new Argyll and Bute unitary authority.