The Nebuly Coat by J. Meade Falkner

THE NEBULY COAT is an intriguing mystery featuring a young architect, Edward Westray, who is employed in the sleepy Dorset town of Cullerne supervising restoration work on the decaying Cullerne Minster. There he becomes involved in a mystery surrounding the claim to the title of Lord Blandamer, whose coat of arms hangs in a window of the minster, and whom Westray comes to suspect is not whom he seems.