He married Princess Antonia of Prussia (who no longer uses her royal title) on 3 February 1977 at St. Paul's Church, Knightsbridge,London. Princess Antonia of Prussia, Duchess of Wellington, Duchess of Ciudad Rodrigo, OBE (born 28 April 1955), is a great-granddaughter of Wilhelm II, German Emperor and is descended from Queen Victoria through her daughter, Princess Victoria
. Antonia Elizabeth Brigid Louise Mansfeld was born in London on 28 April 1955, the daughter of Prince Frederick of Prussia and Lady Brigid Katherine Rachel Guinness, daughter of Rupert Guinness, 2nd Earl of Iveagh. She is the twin sister of Prince Rupert Alexander Frederick. She was educated at Cobham Hall School and King's College London (BA, English). She was awarded the OBE in the 2008 Birthday Honours for services to social housing as President of the Guiness Trust.