Mountbatten was born on 17 March 1966 to Colin G. Thompson and Rosemary Vere Edwards.

[1] Her parents later divorced and her mother remarried Tim Walker.

[2] On 23 April 1994 she married Lord Ivar Mountbatten, a third cousin-once removed of Elizabeth II,[3] at St Peter and St Paul's Church, Clare in a ceremony attended by Princess Margaret, Countess of Snowdon and Prince Edward.

[2] She succeeded her ex-husband's first cousin once-removed, Lady Pamela Hicks, as patron.

[7] Mountbatten owns and manages Penny Mountbatten London, a luxury brand representation and event management firm, which has several royal warranted labels.