Margrit's apartment is very nice, modern, and well equipped, located in an upscale neighborhood in west London, just meters from a main street and only a couple blocks away from a tube station (circle line) that takes you to all of the main attractions along the river or connects you with many other lines. You even have a Waitrose supermarket across the street.
Huw deserves a special mention because he was such a great host. He always kept in touch both before and during our stay, and even after our stay to make sure we got to the airport in time (with a transfer service he sorted for us). A very kind and attentive host.
I'll be staying in this flat on my next trip to London without hesitation.