The first creation came in the Peerage of Great Britain on 21 August 1786 when the soldier and administrator Sir Guy Carleton was made Lord Dorchester, Baron of Dorchester, in the County of Oxford.

Richard Carleton, seventh son of the first Baron.

The title was revived on 2 August 1899 when the Honourable Henrietta Anne Carleton was made Baroness Dorchester, of Dorchester, in the County of Oxford, in the Peerage of the United Kingdom.

She was the wife of, firstly, Francis Paynton Pigott and, secondly, of Major-General Richard Langford Leir.

He had two daughters but no sons, and on his death in 1963, the title became extinct for the second time.