Dormant, Abeyant, Forfeited, and Extinct Peerages @ p. 524, Swynnerton, Baron Swynnerton
The cited information was published by Burke's Peerage, Ltd., London, England, 1883, held in
{R500171218} (Ref: p. 524, Swynnerton, Baron Swynnerton) The author/originator was Sir Bernard Burke.