[1] After Edinburgh Castle was recovered from William Kirkcaldy of Grange in May 1573, George Douglas was appointed its Captain or keeper by his half-brother Regent Morton.
[2] George Douglas supervised the rebuilding of part of the back wall and other repairs, buying lime, sand, slate and glass.
[4] Parkhead is credited with building the half-moon battery at Edinburgh castle, the Historie of King James the Sext records that Regent Morton appointed him captain, and caused "masonis to begin to redd (clear away) the bruisit wallis, and to repaire the foirwark to the forme of ane bulwark, platt and braid above, for the resett and ryving (receiving) of many canonis.
[7] When his brother resigned the regency of Scotland in March 1579, George Douglas of Parkhead made an inventory of the personal jewellery of Mary, Queen of Scots kept in Edinburgh Castle, and of the textiles, the royal tapestries, Mary's remaining costume, her pictures, dolls, and library, and he itemised the artillery of the castle and the tools in its workshops.
[11] Parkhead wrote to Francis Walsingham in June 1582 to thank him for hospitality in England, mentioning his friend John Selby of the garrison of Berwick-upon-Tweed.
[17] On 20 December 1593 George Douglas and his son James made over some of their lead mining rights in Glengonnar to the goldsmith and financier Thomas Foulis.
[18] An English prospector Stephen Atkinson writing in 1619 stated that "George Parkhead" was killed by a landslide in wet weather at a mine working at "Short-clough brayes".