The interior of Annandale House is a living monument to the Victorian style of design, known as the "Aesthetic Art Movement."

Followers of the movement included the architect John Ruskin, the designer William Morris, the American painter James Whistler and the most vocal supporter, author and playwright Oscar Wilde.

Aestheticism can be found in the wall coverings, painted ceilings, fireplaces, stained and etched glass and carved into the woodwork.

Annandale House is one of the few surviving examples of homes decorated in this style in Canada.

Irish author, poet and playwright, Oscar Wilde was the most vocal supporter of this movement and in 1882 gave his lecture The House Beautiful in Woodstock, Ontario[4] in which he said “And so I said, find your subjects in everyday life; your own men and women, your own flowers and fields, your own hills and mountains, these are what your art should represent to you.”[5] Mary Ann Tillson attended his lecture and listened to this unusual man.