Death at the Dutch House (Constable 1997)
Julia Bransby is appalled when the owner of the beautiful seventeenth century Dutch House decides to open it to the public. Not that Cherry Ducket-Penrose's historic family home isn't worthy of display. It's just that the eccentric Cherry is none to particular about her standards of cleanliness and presentation and, more worryingly, the Dutch House if full of very valuable antiques and low on security.
Part of the Dutch House has been converted into flats, inhabited by a diverse but fairly harmonious group of people, and despite Julia's misgivings more or less everyone rallies round at the opening. Even the follow-up from the local antique dealers seems fairly harmless. Then disaster strikes. One of the Dutch House community is found brutally murdered, and a selection of her most valuable antiques is missing.
Detective Robert Southwell is assigned to the case. At first he thinks the murderer must be someone from outside but he changes his mind as he discovers that not all is as it seems in the apparently respectable lives of the flat-dwellers.