مستشفى سانت ماري
Matthews' father is Laird of Glen Affric, a 10,000 acre estate in Scotland. Matthews' inheritance of the lairdship will result in Middleton "acquiring" the courtesy title of Lady Glen Affric. Their son Arthur Michael William was born on 15 October 2018 at St Mary's Hospital, London. Their daughter Grace Elizabeth Jane was born on 15 March 2021.