 The work was so highly esteemed by James Beaton, archbishop of Glasgow, that he recommended Queen Mary to bestow on him the office of counsellor or judge of the parliament of Poitiers, the province of Poitou having by letters patent from Henry III been assigned to her in payment of a dowry.Some misunderstanding regarding the nature of this office seems to have given rise to the statement of Mackenzie and others that Blackwood was professor of civil law at Poitiers.At Poitiers he collected an extensive library, and, encouraged by the success of his previous work, he set himself to the hard and ambitious task of grappling with George Buchanan, whose views he denounced with great bitterness and severity in "Apologia pro Regibus, adversus Georgii Buchanani Dialogum de Jure Regni apud Scotos", Pictavis, (1581) and Parisiis, (1588).