The Windmill on Clapham Common is a gastropub mentioned in The Cuckoo’s Calling, Part 2, Chapter 10. 

At this point in the series, Robin and Matthew are living in Clapham, an area south of the Thames. “She and Matthew had eaten lunch, in company with two friends of Matthew’s, at his favourite gastropub, the Windmill on the Common. When Robin had spotted the picture of Evan Duffield in an open copy of News of the World at a nearby table, she had made a breathless excuse, right in the middle of one of Matthew’s stories, and hurried outside to text Strike.”

“Matthew had said, later, that she had shown bad manners, and even worse not to explain what she was up to, in favour of maintaining that ludicrous air of mystery.”

When we were at the Windmill, we didn’t have time for a bite or a pint, but it looked to be a happening place. If you can get over the fact that it’s Matthew’s favourite gastropub, then you can find it here:

Clapham is an area of London where J.K. Rowling once lived, so she clearly knows the area quite well. She even writes on the official Harry Potter fansite, Pottermore, that “two Muggle dog-walkers found themselves accidentally transported to a Celestina Warbeck concert in 2003, because their dogs had run off with an old trainer on Clapham Common.” The old trainer was, in fact, a Portkey, an object used to transport wizards and witches from place to place.