I read this book about 8 years ago. It was a creepy story,about a man who was in a steady,but dull marriage.
The details I can remember are:-
He belongs to a gentleman's club in London.
He owns an estate in the north of England (or possibly Scotland) that he inherited from his parents.
He starts having hallucinations whilst he's staying at this estate,triggered by a painting that he sees while visiting a friend in Ireland.
His wife discovers that he is not all that he seems.
Can anyone help?