I have two documents with the seal and signature of Walter Francis, Duke of Buccleuch and Queensberry stating that two men (brothers?) were being made 'cornets' in the Royal Mid-Lothian or Edinburgh Yeomanry. This was in 1858 and 1859. What is, or was, a 'cornet'?
In the Foot Regiments there was a rank of Ensign and in the Cavalry Regiments (which the Yeomanry are) the same rank was called Cornet. Both Ensign and Cornet were generally done away with in 1871 and replaced with the commissioned officer rank of Second Lieutenant. However, a small number of Cavalry Regiments even now retain the rank of Cornet including the Blues and Royals, and both Prince William and Prince Harry are currently each known as Cornet Wales.