[artifact]

This one has been driving me bonkers of late so I'm throwing myself on the memory of Mobileread's romance fans:

* A Regency romance (might be borderline Victorian.)
* A big name author like Hawkins, Quinn, Balogh, etc but I can't find this book among their works.
* Not the Signet or Zebra line but near that era.
* About double the thickness of the above (probably due to text size and formatting.)
* Starts with S, and I think the cover was blue/purple with a manor house on it. NOT Skylark, Splendid (whose covers fit this.)
* The hero was a dandy that wore clocked stockings. I think he was an ex-spy as well. Heroes are never dandies so the fact he is one makes it stand out.
* Set in the country, not London. The heroine lived in the manor house next door or close by.
* The plot was focused around one of the manor houses. A mystery, treasure, treasonous secrets, or something similar.