It is extremely difficult to disentangle the careers of the various William Herberts who were contemporaries in early Stuart Glamorgan. The major confusion arises between this Member’s family and the Herberts of Cogan Pill, near Cardiff, a difficulty compounded by the fact that these two branches were linked intimately and even administered one another’s lands. Some success in differentiating between them has been achieved by comparing signatures in key documents, but this Member’s office-holding career remains partly conjectural.
Herbert was descended from Richard Herbert of Ewyas, the bastard son of the Yorkist 1st earl of Pembroke, a family which produced a number Glamorgan MPs under the Tudors.
It was probably shortly after this move that Herbert took charge of local affairs for his kinsman William, 3rd earl of Pembroke, whose mother resided at Cardiff castle.
Herbert continued to be a loyal Pembroke servant after the death of the dowager Countess in October 1621, advising his cousin to warn the earl of the need for protection from ‘those that care not for any of our name.’
Despite his close relationship with Pembroke, Herbert was almost certainly the ‘ungrateful kinsman’ who yielded Cardiff castle to the royalists in 1642.
