The Doctor was hanging around the 18th century, perhaps looking for another companion. He was walking down a side street following a stray dog. He looked around him, taking in the wonderful 18th century buildings and the women in beautiful dresses. He stopped for a second and admired his surroundings momentarily, before following the dog once again.
He followed around a sharp corner and briefly saw a blue police box. It had just left; he only caught a slight glimpse. At first he thought someone had stolen his TARDIS, but no, he hadn't parked it here. Then it came to him. He remembered it, hundreds of years ago. He had been in this same place, just after an encounter with the Cyber men. He remembered seeing a little black stray dog barking happily before he closed his TARDIS door behind him.