Fig. 669.—Arms of Arbroath: Gules, a portcullis with chains pendent or. Motto: "Propter Libertatem." Supporters: dexter, St. Thomas à Becket in his archiepiscopal robes all proper; sinister, a Baron of Scotland armed cap-à-pie, holding in his exterior hand the letter from the Convention of the Scottish Estates, held at Arbroath in the year of 1320, addressed to Pope John XXII., all proper.
<bdi><a href="https://en.wikipedia.org/wiki/en:Arthur_Charles_Fox-Davies" class="extiw" title="w:en:Arthur Charles Fox-Davies"><span title="British writer (1871-1928)">Arthur Charles Fox-Davies</span></a>
</bdi>
A Complete Guide to Heraldry.