This castle was captured by the English in 1497, and the nearby church was the scene of the subsequent negotiation of the treaty of Ayton, signed on 30 September 1497.

After further inheriting the Stow estates from a distant cousin, he hyphenated his surname and is found as William Mitchell-Innes of Parsonsgreen, an ordinary director of the bank, 1841–1853.

In 1851 William Mitchell-Innes commissioned James Gillespie Graham to build a new castle at Ayton in the Scottish Baronial style in red sandstone.

Extensive interior redecoration was carried out in 1875 by Bonnar & Carfrae, still largely extant, with stencilled imitation silk damask.

Mention must be made of the visit to the castle in 1873 by Mark Twain, who insisted upon buying the dining room fireplace mantel.

Alexander Mitchell-Innes married (1) Charlotte (1818–1848), daughter of Sir Thomas Dick Lauder of Fountainhall, 7th Bt.

Alexander Mitchell-Innes had apparently shared his entire estate with his very large family and they were accordingly all paid out following the sale of Ayton Castle.