Even though I visited London plenty as a child, and later lived there, the London of the Monopoly board still somehow forms part of my map of the city. And it makes no bloody sense. This map has a few things wrong with it (also pointed out on the reddit thread where I found it. The orange properties (which make the least sense of any of the groupings) are definitely in the wrong places. I always thought that 'Marlborough Street' had to be 'Great Marlborough Street'. I went looking for a better map and found this Google Maps plot that looks a bit better.
This article in the Londonist also points out that there's technically not a Bond Street, only New or Old ones, and the coaching inn called The Angel at Islington that the game used isn't there anymore though there's apparently a branch of Wetherspoons under that name now (which somehow surprises me not a jot).
And now I've discovered someone has written a whole book on this kind of tangent: Do Not Pass Go by Tim Moore..