When the day arrived Julius needed a considerable amount of persuading, but Tuppence held firm. “It can do no harm,” was what she always came back to. In the end Julius gave in, and they proceeded in the car to Carlton House Terrace.

The door was opened by an irreproachable butler. Tuppence felt a little nervous. After all, perhaps it was colossal cheek on her part. She had decided not to ask if Sir James was “at home,” but to adopt a more personal attitude.

“Will you ask Sir James if I can see him for a few minutes? I have an important message for him.”

The butler retired, returning a moment or two later.

“Sir James will see you. Will you step this way?”