The title was created in the Peerage honours of Great Britain in 1793 for Henry Herbert, 1st Baron Porchester. The precise form of this creation was "Earl of the Town and County of Carnarvon," in the Principality of Wales (although in practice only the style of "Earl of Carnarvon" is used).

So Tigger... you are right. The fifth Earl, George Edward Stanhope Molyneux Herbert, 5th Earl of Carnarvon also inherited the title of Baron of Porchester along with all other titles originally granted and amongst his fellow archaeological friends during his time in Egypt was refered to as "Porchy" though not by his 'employee' Howard Carter.

The Barony of Porchester lies in the English county of Hampshire.