Clarence House | Royal resid., 1 of many royal bldgs. in London, on The Mall, in the City of Westminster. It's attached to St. James's Palace & shares its garden. Home to Elizabeth, the Queen Mother, 1953-2002; it's since been the offic. resid. of Charles, Prince of Wales/Camilla, Duchess of Cornwall. It was the offic. resid. for Prince William from 2003 to his 2011 marriage/Prince Harry from 2003-2012. Open to visit. for approx. 1 mo/summer, usually Aug.