[1] Bernard Burke, in his a Genealogical and Heraldic Dictionary of the Peerage and Baronetage of the British Empire, agrees with Roland Saint-Clair and says that Henry Sinclair was "in reality" the fourth holder of the title of Lord Sinclair.

[2] William Sinclair, 3rd Lord Sinclair was reportedly disinherited by his father who had favored his two eldest sons from his second marriage to Marjory Sutherland: he passed the title and lands of the Barony of Roslin to the eldest son from his second marriage, Oliver Sinclair, and the earldom of Caithness to his second son from his second marriage, another William Sinclair.

According to Roland Saint-Clair, the most likely reason is that William Sinclair, 3rd Lord Sinclair, whilst the Master of Orkney, having imprisoned William Tulloch the Bishop of Orkney was the main reason why his father had lost the earldom of Orkney.

[1] William Sinclair, 3rd Lord Sinclair, recorded as "of Newburgh" reached an agreement with his half brother Oliver Sinclair, in which William would receive the lands of Cousland in the sheriffdom of Edinburgh, the barony of Dysart Castle and lands of Ravenscraig, Dulbo, Carbary, and Wilstoun in Fife in return for him and his son Henry renouncing their claims to the Barony of Roslin and it's attached lands.

[5][2][6] Ravenscraig Castle was the seat of the Lords Sinclair.