I enjoy the Corduroy Mansions series, but I do feel that Alexander McCall Smith never really gets to grips with London in the same way that he handles Edinburgh - this is, of course, unsurprising, as he is an Edinburgh resident. Without the numerous references to real places (Valvonna & Crolla, the Scottish Gallery, etc) and people, the London books seem to me less compelling. There is nothing "London" about the characters, as there is "Edinburgh" about Angus Lordie and Cyril. The characters in A Conspiracy of Friends could really be anywhere.
Having said that, I do think this series is improving as it goes along, and as the characters become better defined. I now really want to know what is going to happen to William and Freddie De La Hay - Alexander McCall Smith definitely has a way with writing about dogs.
As one of the previous reviewers says, these books are extremely comforting, with some laugh out loud moments. I will most certainly look forward to the next instalment, even though Scotland Street will always be my favourite series.