My fiancée and I stayed for 10 days in Kieran's place and we were delighted with everything. The attic is fantastic: it has plenty of natural light, the bed is very comfortable and the (private) bathroom is super tidy with all the necessities covered. Moreover, it is placed in a very nice and quiet location, around 5 minutes walking from the Northfields station (Piccadilly line) and with very nice restaurants and parks around.
The treat of Kieran and William was fantastic: they recommend us plenty of beautiful places to visit around and restaurants where we could have lunch and work, they solved all the issues we had and give us useful advices regarding how to reach different places with the metro.
In short, we highly recommend Kieran's place either if you are going to do tourism or to work around!!