|Type:||Castle of Enceinte|
|Built 11th century|
Bonkyll Castle (also variously spelled Bonkyl, Boncle, Buncle, Bunkle or Bonkill) was a mediæval fortress in the Merse of Berwickshire, and though once a strong fortress, little now remains. The site is protected as a scheduled monument.
The village where the castle stood, Bonkyl has since vanished beneath the fields.
Excepting the motte on which it stood, and a small section of curtain wall there is little left of the structure of what was once a very powerful castle of enceinte.
The castle was the caput of the wealthy Honour of Bonkyll. It originally belonged to the eponymous Bonkyl family, passing by marriage in the late 13th century to Sir John Stewart, son of Alexander Stewart, 4th High Steward of Scotland. Sir John's grandson, also Sir John Stewart married Margaret de Abernethy, the heiress of the Lordship of Abernethy in 1328 and the following year he was created Earl of Angus, thus combining broad territories in Berwickshire, Angus, and Kinross-shire. Sir John's granddaughter, Margaret Stewart, being his sole heiress inherited the Earldom of Angus and Lordship of Abernethy, and the honour of Bunkle. She had an illicit affair with William Douglas, 1st Earl of Douglas, of which liaison, a child was produced, George Douglas, 1st Earl of Angus. From the Countess Margaret's death in 1417 Bunkle remained under the ownership of the Douglas Earls of Angus until the late 18th century when it passed to the Earls of Home.
A popular Berwickshire rhyme refers to the mediæval strengths of Bonkyll and the nearby fortresses of Billie Castle, and Blanerne Castle referring to their construction in the time of David I and their destruction following Henry VIII's campaigns known as the 'Rough Wooing':
Bunkle, Billie and Blanerne
Three castles strong as airn
Built when Davie was a Bairn
Theyll all gang doon,
Wi Scotland's Croon
An ilka ane shall be a cairn