Here is the official statement concerning Nancy Reagan's injury from Cathy Busch, a spokeswoman for Nancy Reagan (search):

Early this morning Mrs. Reagan took a fall in her hotel room in London and was taken to a nearby hospital. After a thorough examination she was released and returned to the hotel. She will be following her doctor's advice to limit her activities over the next two weeks until the pain subsides and full mobility returns.

While in London Mrs. Reagan had tea with Lady Thatcher (search) and was received by TRH's The Prince of Wales and The Duchess of Cornwall at Clarence House (search).