I stayed a month at Olivier's place. It was a good stay, but some things can be improved to make it a pleasant one.
Very good communication with Olivier and his girlfriend; they were very helpful. The apartment is very close to Earl's Court station, from where it takes you 10-15 min to reach the central London. It is also a 15 min walk from museums and other places of interest (V&A etc).
The apartment is on the lower ground floor (basement) which is not clearly seen in the pictures. The only thing I would suggest changing is the cheap IKEA bed which is very uncomfortable and investing in some nice pillows and sheets. Olivier expected me to leave the apartment clean as I received it, despite the Cleaning fee included in the price - clearer rules will be a plus to everyone :)
Thanks for staying at your apartment, Olivier.