Look to the Lady written by Margery Allingham performed by Philip Franks on Audio CD (Abridged)

The Gyrth family had guarded the Chalice for hundreds of years. It was held by them for the Crown. Its antiquity, its beauty, the extraordinary legends that were connected with it, all combined to make it unique of its kind. It was irreplaceable. No thief could hope to dispose of it in the ordinary way. And indeed...

no ordinary thief would dream of trying. But there are others besides those who make their living by robbery, others whose immense wealth and passion for collecting render them less immune to the practical considerations that must guide even the less honestly minded citizens.

These people cherish a desire to possess for their own private pleasure treasure that cannot be bought. And it was by this sort of person that the Chalice, and the lives and happiness of its guardians, were now threatened.