Now I haven't been to Turkey - but foodwise I feel as though I have.
This place is simply the best. I have been to many parts of the world and am yet to find a doner/shawerma place of this quality. The meat they use, the super fresh salad, the fresh chilli sauce, and the unquestionable service, make this one of the must stops during any visit to London.
My father introduced me to this place in 1989. He and his study mates in the Seventies would make the trip from all over England for the then only halal place in London. In 2008, the owners are still the same and the quality is the same if not better.
In true Bosphorus style, please post your comments about the place and I will share these with the people during my next visit. For those who don't know, the restaurant walls are covered with comments from customers from all over the world.
I highly recommed the "Lamb Burger" - but honestly all their grilled food is excellent.
Location is at 59 Old Brompton Road - South Kensington. More information here.