Catherine Worsley (nee Hirtz) wife of Peter Marcus Worsley (b. 1963), gave birth to a daughter, Matilda Bridget, 17 December, 2005, a sister for Margot and Hector.
Peter Worsley is the youngest son of Sir Marcus Worsley, 5th Baronet, by his wife the former Hon. Bridget Assheton, & is a nephew of HRH The Duchess of Kent; Catherine Worsley is the youngest daughter of M and Mme Jean-Marie Hirtz, of Paris.
Source: Daily Telegraph 5 January, 2006