Coat of arms of Alexander Cambridge, 1st Earl of Athlone (1874-1957), third son of Prince Francis, Duke of Teck (a German nobleman), and Princess Mary Adelaide of Cambridge, daughter of Prince Adolphus, Duke of Cambridge (1774-1850), the youngest surviving son of King George III. Quarterly of 4 with a crescent sable overall for difference (usually of a second son):
1&amp;4: Royal arms of Prince Adolphus, Duke of Cambridge (1774-1850), being arms of his father King George III with label for difference;
2&amp;3: Arms of Prince Francis, Duke of Teck
SVG elements from

Mary_of_Teck_Arms.svg
Croissant_d_or.svg
A1 Aardvark