The Cavalier's Cup (Sir Henry Merrivale, #22)

Pan Books #G412.

A singular request from the young and delectable Lady Brace starts Sir Henry Merrivale on his most diverting case.
Uneasily teamed with his old rival, Chief Inspector Masters of Scotland Yard, the indefatigable 'H.M.' investigates the extraordinary happenings in the seventeenth-century Oak Room at Old Telford Hall - home of the fabulous Cavalier's Cup.