Slightly out of breath, she came to a halt outside the ground glass door with the legend painted across it “Estonia Glassware Co. ”

Tuppence knocked. In response to a voice from within, she turned the handle and walked into a small rather dirty outer office.

A middle-aged clerk got down from a high stool at a desk near the window and came towards her inquiringly.

“I have an appointment with Mr. Whittington,” said Tuppence.

“Will you come this way, please.” He crossed to a partition door with “Private” on it, knocked, then opened the door and stood aside to let her pass in.