"The story of Prince Andrew and the teddy bears is very revealing. Various members of staff who've worked for him have told me this is very typical of him..."
According to a new joint interview with writers Steven Moffat and Russell T Davies, thinking of the Doctor as segmented incarnations isn't really how they approach writing the character at all. In fact, instead of the great differences between incarnations, (that fans love) to debate, Moffat and Davies seem to indicate that they never aim to write the Doctor particularly differently and that thinking of the character as a constant is the paradoxical secret to making each version feel authentic.