Once Upon A Mattress(2005)

Tracey Ullmann in the third remake of this Broadway classic.

Queen Aggravain has ruled that none may marry until her son, Prince Dauntless marries. However, she has managed to sabotage every princess that come along. When Sir Harry and Lady Larken learn that they are going to be parents, wed or not, he goes off to the swamps and brings back Princess Winnifred ("Fred" to her friends).