Do I need to know the ending before I begin?

Do I need to know the ending before I begin?

Russell Celyn Jones (Published writer. Professor of Creative Writing and Director of the MA Programme at Birkbeck College (University of London).) gives expert video advice on: What's the difference between plot' and story'?; Do I need to know the ending before I begin?; Are there rules for structuring a novel? and more...

I don't think a writer needs to know the ending of a book because even if you do think you know the end of a book, when you start writing the chances are it will change anyway because your characters change in the process of writing the book. So have an ending by all means, but don't anticipate it's going to stay the same.