Friar Mark is known for his history of the origins of the Hamilton family, identified as an important document for the culture of the Scottish court in the time of Arran's Regency, (1543-1554).
[6] The History states that Robert the Bruce gave the lands of Kinneil to Gilbert Hamilton, "for his trew service and greit manheid," and especially for having slain "for King Robertis pleasour the great lieutennand of Yngland upon Kynnale Muir. "
[7] For Sir Gilbert's exploit on Kinneil Muir vanquishing "Odomar Vallance" the Welsh-born Lieutenant of Edward II of England, Friar Mark tells us, "King Robert gaif till him his armis till weir in Scotland thre sink fuilzies in ane bludy field," or modernised: King Robert gave to him forever to wear in heraldry in Scotland three cinquefoils in a blood red field.
Friar Mark says the younger brother Walter fitz Gilbert was red haired and ruddy in complexion, traits inherited from his Scottish mother.
[10] Friar Mark wrote that Isabella of Mar was; "ane of the warldliest ladiest that was in that tyme scho was King Robertis sister douchtir and till erle Thomas Randell his full sister quhais name was callit Isobell ane madin of twenty yeris of aige of vertew & of greit honour maist excelling undir the quene for that tyme".