Mary's house is actually a little hotel. The hosts are not home and there is no living space outside space. The kitchen is small but available to all guests.
The apt I stayed in had its private, tinny bathroom. Heating but not Air Conditioning. Very clean and quite tight.
A train station is a block away from the house. It is important to point out that this place is not very close to the main attractions of London. 35 to 40 minutes by tube. Bis will yake close to an hour.
There is a small pub/rest in the corner. It closes promptly at midnight. Very british.
Overall good sleeping conditions but very far from London center. Given these I believe it is a bit overpriced