The name Leirmont was among Malcolm III's supporters described for the first time by Hector Boece in his "Scotorum historiae a prima gentis origine" printed in Paris in 1527: Ili primi fuere comites quorum nostri meminerunt anales.

Multarum nova cognomia Scotorum familiis indita, Calder, Locart, Gordon, Setoun, Gallora, Laudir, Wawaim, Meldrun, Shaw, Leirmaont, Libert, Straquhyn, Cargil, Ratra, Doundas, Cocburn, Mar, Menzees, Abbercromme, Lesbei, Myrtoun multaque alia praediorum nomina, quibus viri fortes a rege donati in munerum concessere cognomina.

[3] Learmonth was a witness to a legal instrument made at Falkland Palace on the death of James V, which purported to make Cardinal Beaton as Regent or Governor of Scotland.

Dunning's [6] fundamental story about the Russia's First Civil War in 1598–1613, Peter Learmonth entered Swedish service in 1603 as an ensign, and he rose through the ranks in Colonel James Spens’s regiment.

[7] In 1610 Peter Learmonth served as a captain in the Swedish army that was invited by Tsar Vasilii Shuiskii to enter Russia to oppose Polish military intervention.