The Royal arms with a label for difference are for H.R.H. Prince William Frederick, 2nd Duke of Gloucester, nephew of King George III.
William Frederick, 2nd Duke of Gloucester, was the son of Prince William Henry, 1st Duke of Gloucester (d.1805) and Maria, Countess of Walpole (d.1807). He was born at Teodoli Palace in Rome, where his parents were stationed in order to avoid the censure of his father's older brother, George III, who considered the match inappropriate, since Maria was illegitimate and divorced.
Prince William returned to England, entered the army in 1789 at the age of thirteen, and was quickly promoted; he was a general by 1808 and a field marshal in 1816. He enjoyed academic success as well, and despite his nickname 'Silly Billy,' he earned two degrees from Trinity College, Cambridge, and was later elected a fellow of the Royal Society, and chancellor to the University of Cambridge in 1811.
Prince William unsuccessfully courted Princess Charlotte (1796-1817), daughter of George IV (1762-1830), and settled instead on his first cousin, Princess Mary (1776-1857), or 'Dearest Minny,' who was widely considered the most beautiful of the daughters of George III and Queen Charlotte. Prince William and Princess Mary were married in 1816.
Prince William supported the abolition of slavery (both in Parliament and as president of the African Institution) and Catholic emancipation. He supported the Duke of Sussex during the Regency and advocated for Queen Caroline during the proceedings against her in Parliament. His comical appearance made him a fine target for political cartoonists, who referred to him as 'Slice of Gloucester and Cheese.'
William Frederick, 2nd Duke of Gloucester (1776-1834)
Courtesy Christie's Images