 In 1746, he began cohabiting with his mistress, Margaret, Countess of Orford, whom he married on 25 May 1751, shortly after the death of her long-estranged husband, the 2nd Earl of Orford.After three years of close attachment, they separated in June 1754.Margaret had taken care to legally protect her own estates and jointure, so that Shirley could have no claims on her property.