On the way to the castle, we stopped and I bought a London street directory, called the "A to Z". It's somewhat like a Gregory's map, except this particular one has pages about half the size, and they are spiral bound. This was suggested as a good starting point for my next trip, which was to drive to SE London and find a house in Beckenham.
It's not too hard to find. I had a route planned, but took a couple of wrong turns, requiring some back tracking. Eventually I decided I wasn't on the route I had planned, so pulled off and found a street with an uncommon name, and looked it up in the directory. It turned out that I had followed a better route than the one I planned. And was less than a kilometre from Dave's home.
And what a home it is. Far and away the nicest home I stayed in. Dave is married, with 2 children - one just teething, the other one about 8 years old. I had a bedroom which is about as big as the entire upstairs of my home. And it's a very nice area - obviously the better off end of town. And only about 15 minutes by train to the city. And Dave and Pauline made me feel very welcome.