Lewis was born in St John's Wood, London, the son of Charlotte Mary (née Bowater) and J. Watcyn Lewis, a City broker. His paternal grandparents were Welsh. His maternal grandfather was Lord Mayor of LondonSir Ian Bowater and his maternal grandmother's ancestors include Lord Dawson of Penn (a doctor to the Royal Family) and the philanthropist Alfred Yarrow. He has stated that he "went to English boarding schools and grew up around people very much like Soames and in a milieu very much like the Forsytes'".
Byron finds a gang of kindred spirits in the mesmerizing LadyDie (Lewis), Sticky Nikki (Thomas-Smith), DirtyDamian (Ali), while an intense rivalry brews between Byron and the beautiful, acid-tongued Sasha (Jones).” .
Indeed, the late queen’s blood is still being sluiced from the block as her dangerously fickle husband (played by DamianLewis) utters his wedding vows for the third time to Kate Phillips’ Jane Seymour.