The Marquess will work as a Lord-in-Waiting for the King.
Their home, Houghton Hall, is near where Prince William and Kate Middleton live.
Grandmother of the Marchioness was a bridesmaid in Queen Elizabeth's wedding.
Anmer Hall, the home of Prince William and Kate, is close to the Queen's Sandringham estate.
After David was replaced as Lord Great Chamberlain last year, the Marquess and Marchioness will get their titles back.