Sir Richard Herbert of Ewyas - Birth Year - From the following publications on Wikipedia - May i Suggest Circa 1444 -(this would correspond then to an Age of 21 - for a Grant of Land & Manors. despite his illegitimacy).

The titles and estates of the Earl of Pembroke descended to Herbert's younger, legitimate half-brother William,[4] but he achieved notability through his own merit and through his descendants: "Sir Richard Herbert, of Ewyas, who, though illegitimate, is ancestor of the men who have really, in modern times, rendered the name of Herbert illustrious."[6]

In 1465, Richard Herbert was granted Westminster, manors of Grove, Radnore, Mookas, Brutescourt, Throuckeston, Westhide, Egelton, Redehire, Howton and Wormeton Tirell, in Herefordshire.[7]