Royal Wedding a 1951 MGM musical comedy film starring Fred Astaire, Jane Powell among others.
Directed by Stanley Donen, with music by Burton Lane and lyrics by Alan Jay Lerner
With the success of their Broadway show Every Night At Seven, Tom Fred and Ellen Bowen Jane, a brother and sister team, were persuaded to take the show to 1947 London at the time of a royal wedding about to happen, Princess Elizabeth and Philip Mountbatten, Duke of Edinburgh.
A love story for both gets really tangled, but the dancing is as free as it can be. Enjoy.
DVD available at http://www.taplegacystore.com