Dear Sara ~
Below is my current file account regarding Maud de Brus and her husband, Thomas Isaac, Esq. (also known as Thomas son of Isaac). Her given name was Maud. Matilda is the Latin form of her name.
Thomas Isaac appears to have owned no lands in his own right in Scotland, which suggests the possibility that he was from outside of Scotland. He certainly had no title. I suppose he might have been French, as we know that Maud was living in France from 1334 to 1341. Soon after Maud's return to Scotland, she married Thomas Isaac.
Best always, Douglas Richardson, Salt Lake City, Utah
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MAUD DE BRUS, daughter by her father’s 2nd marriage. She was sent to France in 1334 along with her brother, King David II of Scotland, and her sister, Margaret, for their safety. They returned to Scotland in 1341. She married after June 1342 but before 1345 THOMAS ISAAC (or YSAK), Esq. They had two daughters, Janet and Katherine. In 1342 Thomas son of Isaac was paid £6 12s. 6d. “until otherwise provided for.” At an unknown date, his wife, Maud, was granted half of the thanage of Formartine and Kintore, Aberdeenshire by her brother, David II, King of Scots. Maud died at Aberdeen 20 July 1353, and was buried in the abbey church of Dunfermline, Fife by her parents. THOMAS ISAAC, Esq., was living in Nov. 1364.
Rymer, Fœdera 6 (1727): 105–106 (Thomas Isaac styled “nobleman” in 1358). Brydges, Collins’ Peerage of England 5 (1812): 111–129 (sub Earl of Aylesbury). Hodgson, Hist. of Northumberland Pt. 2 Vol. 3 (1840): 6–8 (ped.). Paterson Hist. of Ayr 2 (1852): 271. Riddell, Comments on the Keir Performance with Drumpellier’s Exposition (1860): 189 (“Antecedent entry in the Exchequer Roll of David II., that in 1328 [sic] the Thanedom of Formartin was in the hands of ‘Comitis de Sotherland, et Matilde de Bruce, spouse Thome Isaac; ’ thus confirming Fordun’s account of the marriage.”). Skene, Johannis de Fordun Chronica Gentis Scotorum (Historians of Scotland 1) (1871): 369–370 (“Obiit Matildis de Bruyse, soror domini David regis Scociæ, anno MCCCLIII , apud Abbirden, in festo beatæ Margaretæ virginis, et sepulta est in Dunfermlyn cum parentibus suis,quæ nupsit cuidam armigero, nominee Thomæ Ysaac…”). Stuart & Burnett, Rotuli Scaccarii Regum Scotorum 1 (1878): cxxviii, note 1, 510, 545–546, 551 (Maud de Brus, wife of Thomas Isaac, styled “sister of the king”); 2: 132. Skene, Liber Pluscardensis 1 (Historians of Scotland 7) (1877): 239–240; 2 (Historians of Scotland 10) (1880): 103–104, 184–185. Bain, Cal. Docs. Rel. Scotland 1108–1509 4 (1888): 4. Temple, Thanage of Fermartyn (1894): 20. Scots Peerage 1 (1904): 8 (sub Kings of Scotland). Dunbar, Scottish Kings (1906): 141–142. C.P. 8 (1932): 138–143 (sub Lorn). Fryde, Handbook of British Chron. (1986): 59. Grant & Stringer, Medieval Scotland: Crown, Lordship & Community (1993): 66, 74–75. TG 12 (1998): 251. Burke’s Landed Gentry of Great Britain (2001): lxiii–lxv (sub Scottish Royal Lineage). Special thanks go to Andrew B.W. MacEwen for his assistance with this account.