Why did the makers of Elizabeth I (with Cate Blanchett) make Elizabeth - The Goldn Age. (Read Detail)?

It may well be that 'The Golden Age' was considerably cheaper to make.The director,producer,and much of the cast were the same,and may well have signed contracts to make 2 movies about Elizabeth,so wouldn't get another fee for the second movie.Additionally,costumes,sets,models were probably all still around from the first movie,so could be reused,rather than new ones having to be made.There's also the possibility that there was out take and edited film footage from the first movie that could be used in the second,cutting down on filming and production times,further reducing costs.