Before the start of The Cuckoo’s Calling, Cormoran Strike was living with his long-term girlfriend, Charlotte Campbell, whose flat is on Holland Park Avenue. After a massive argument in the early hours of the morning, Strike walks across London from there to his small office on Denmark Street, where he sleeps for an hour or two in his office chair. “It was the first time in their long and turbulent relationship that he had walked out.”
Charlotte’s flat is described in the book as being a “stylish, expensive maisonette…”. In Part 2 Chapter 4, Strike goes back to the flat to pick up his few possessions. “The grand and gracious white buildings that lined the wide street; the plane trees; the butcher’s shop that might have been stuck in the 1950s; the cafés bustling with the upper middle classes; the sleek restaurants; they had always felt slightly unreal and stagey to Strike.”
Charlotte had left his possessions in four cardboard boxes, which he carries down onto the pavement and waits to hail a black cab.
You can find Holland Park Avenue on Google Maps here: