Many other honours were bestowed upon Williams, and in 1865–1867, he was appointed the first Lieutenant Governor of Nova Scotia, where he was born.

He was, however, widely rumoured to be the illegitimate son of Prince Edward, Duke of Kent and Strathearn; this would make him Queen Victoria's half-brother.

He was British commissioner in the conferences preceding the treaty of Erzurum in 1847, and again in the settlement of the Ottoman-Iranian boundary in 1848.

A baronetcy with pension for life, the KCB, the grand cross of the Legion of Honour and of the Order of the Medjidie, the freedom of the City of London with a sword of honour, and the honorary degree of DCL of Oxford University, were the distinctions conferred upon him.

[3][2] Promoted major-general in November 1855 on his return from captivity in Russia, he held the Woolwich command, and represented the borough of Calne in parliament from 1856 to 1859.

After Canadian Confederation in 1867, Williams continued in office as the first Lieutenant Governor of Nova Scotia and the governorship of Gibraltar from September 1870 to 1876.