We loved our stay at Grace and Jan's flat! The apartment is close to everything and even with the Barbican tube station less than a block away, we walked most everywhere. St Paul's Cathedral is as easy as taking a right out of the front door of the flat and walking straight down the road until you run into it. And when you come back from a day of walking and are too tired to eat, there's good pizza at The Shakespeare pub down the street or take a 5 minute walk for delicious Indian takeaway at Cafe Tiffin (they deliver too - we left the menu on the cork board in the kitchen!).
We have stayed in many AirBnB's across Europe and have never had such nice towels and linens as the ones at Grace and Jan's. The towels are big and thick and the beds were just perfect with fluffy pillows and really comfy mattresses. We didn't cook while we were there other than heating up crumpets but there is truly a fully stocked kitchen with a really nice set of knives, which again is very unusual with AirBnB's. You normally get knives that can barely cut cheese but these knives cut right through the big crusty loaves of bread we brought back from Borough Market.
We felt so spoiled by Grace and Jan's flat that we're already planning another trip to London in December and hopefully staying there again if it's not booked.