I don't see the problem. If shops are being priced out of Herne Hill then they would be most welcome in Forest Hill. Perhaps a friendly landlord with a spare shop in Forest Hill could contact Just William and invite them to open in Forest Hill.

Or is there something special about Herne Hill that makes it more valuable to run a toy shop there rather than Forest Hill? And if so, shouldn't they expect to pay a higher rental price than in Forest Hill?