The 16-year period during which Doctor Who was off the air saw television change completely. Multi-camera, studio-bound drama had gone out with dressmaking melodrama The House of Eliott (1991-94); now, virtually all drama was shot single-camera, in the same way that had previously been reserved for film sequences. Improvements in camera technology meant that it was easier, quicker and cheaper to film on location, and it was only cost-eff ective to build studio sets if there was no location available or if the sets were to be used extensively. (The TARDIS interior is a good example.)
This meant that the role of the production designer fundamentally changed, too. Design was less a matter of creating sets and more of finding and dressing locations to fulfil the same function. In addition, because television drama had become a much more expensive and labour-intensive process, the role of the production designer on Doctor Who became more about overseeing all visual elements across not just one episode but the whole series, ensuring that all aspects of design - from sets and costumes to models and CGI - were part of one, unified vision.
Design was less a matter of creating sets and more of finding and dressing locations to fulfil the same function.