The house is very close to the city center via underground but also you can enjoy a very silent neigbourhood. Just 100 meters to Kennington Station and the first stop from here via Northern Line is Waterloo (London Eye, Dungeon), third stop Charing Cross, fourth stop Leicester Square. These places are related with all the major interesting visiting and shopping places in London.
Ian's design work for the house is hugely impressive, many fine details. The house also has a very good library, many interesting books and similar to my reading taste.
The house is generally clean and kitchen equipment is enough to make coffee and tea and even cooking.
Warnings and suggestions for the non British guests.
a.) Traffic is very crowded and taxi fares are high in London city center. You should analyze the underground system before your flight and also remember to check which lines and stations are under improvement (which means not operating).
b.) To go from Heathrow to Ian's place is fairly easy. You should take the Piccadilly Line (blue line) from the Heathrow until the Leicester square and change here to the Northern Line (black line) to the Kennington (southward). That simple. No need to take the special train called Heathrow Express which I did. It is more expensive and complicated.
c.) I enjoyed the music system in the house but I did not understand the tv system. You should ask if you are a tv lover.
d.) No electricity plug adapter for European devices in the house. Bring your own.
It was a great stay and I would like to stay there again in the future.