Everything has been said in previous comments!

This is a suitably sized single bedroom, well-furnished (desk, TV), quiet (only one room at the top floor, view on garden).
Everything is available with a well-appointed kitchen and bathroom (with a washing machine and a dryer). The others roomates were nice and discreet. We were 5 at maximum in the house but we were not disturbed by each other because the rooms are on different floors and we had different work schedules. I rarely waited for the bathroom and there is a convenient separate toilet.
The house is very clean and there are some basic rules for the guests to maintain cleanliness in the common areas.

The area is suburban but safe and well-connected to go to the centre (10 mn walking distance of the metro or 5mn by bus).

Joe is very welcoming and helpful, available to give many advices on London or discuss about many different subjects.