“Do forgive me,” she gabbled. “I mean, of course, I don’t know. I mean, am I right in supposing—?”

Dr Natouche folded his hands, waited a moment and then said: “Are you wondering if I am a British subject? I am. As you see, I belong to a minority group. I practise in Liverpool.” His voice was superbly tranquil and his manner entirely withdrawn.

The silence that followed his little speech was broken by the Skipper who came crabwise down the companionway.

“Well, ladies and gentlemen,” he said. “I hope you are comfortably settled. We’ll be on our way in a few minutes. You will find a certain amount of information in the brochures supplied. We don’t go in for mikes and loudspeakers in the Zodiac but I’m very much at your service to answer questions if I can. The weather forecast is good although at this time of year we sometimes get the Creeper, which is a local name for River fog. It usually comes up at night and can be heavy. During the afternoon we follow the upper reaches of The River through low-lying country to Ramsdyke Lock. We wind about and about quite a lot which some people find confusing. You may have noticed, by the way, that in these parts we don’t talk about The River by name. To the locals it’s always just The River. It was over this country that Archbishop Langton chased King John. But long before that the Romans made the Ramsdyke canal as an addition to The River itself. The waterways were busy in Roman times. We take a little while going through the lock at Ramsdyke and you might fancy a stroll up the field and a look at a hollow alongside the Dyke Way. The wapentake courts were held there in Plantagenet times. Forerunners of our Judges’ Circuits. You can’t miss the wapentake hollow. Matter of five minutes’ walk. Thank you.”

He gave a crisp little nod and returned to the upper deck. An appreciative murmur broke out among the passengers.

“Come,” Mr Bard exclaimed. “Here’s a sensible and heartening start. A handful of nice little facts and a fillip to the imagination. Splendid. Mrs Alleyn, you have finished your luncheon. Do come on deck and witness the departure.”

“I think we should all go up,” Troy said.

“Oh ra-ther!” cried Miss Rickerby-Carrick. “Come on, chaps!”

She blew her nose vigorously and made a dash for the companionway. There was a printed warning at the top: “Please note deeper step” but she disregarded it, plunged headlong through the half-door at the top and could be heard floundering about with startled cries on the other side. Troy overheard Mr Hewson say to Miss Hewson: “To me she seems kind of fabulous,” and Miss Hewson reply: “Maybe she’s one of the Queen’s Beasts’ and they both looked dryly humorous.

Illogically Troy felt irritated with them and exasperated by Miss Rickerby-Carrick who was clearly going to get on everybody’s nerves. Mr Pollock for instance, after contemplating her precipitate exit, muttered: “Isn’t it marvellous!” and Mr Bard, for Troy’s benefit, briefly cast up his eyes and followed the others to the upper deck. Mr Lazenby, who was still at his luncheon, waved his fork to indicate that he would follow later.

Dr Natouche rose and looked out of the saloon windows at the wharf. Troy thought: “How very tall he is.” Taller, she decided, than her husband, who was over six feet. “He’s waiting,” she thought, “for all of us to go up first,” and she found herself standing by him.

“Have you ever done this before, Dr Natouche?” she asked. “Taken a waterways cruise?”

“No,” he said. “Never before. It is a new experience.”

“For me too. I came on an impulse.”

“Indeed? You felt the need of a break perhaps after the strain of your public activities.”

“Yes,” Troy agreed, unaccountably pleased that he did, after all, know of her show and had recognised her. Without so much as noticing that she felt none of her usual awkwardness she said: “They are a bit of a hurdle, these solemn affairs.”

Dr Natouche said: “Some of your works are very beautiful. It gave me great pleasure in London to see them.”

“Did it? I’m glad.”

“They are casting off, if that is the right phrase. Would you like to go up?”

Troy went up on deck. Tom, the boy, had loosed the mooring lines and laid them out smartly. The Skipper was at the wheel. The Zodiac’s engines throbbed. She moved astern, away from her wharf and out into the main stream.

The motor-cyclists were still in the lane. Troy saw young Tom signal, not very openly, to them and they slightly raised their hands in return. The girl straddled her seat, the boy kicked and their engine broke out in pandemonium. The machine, curved, belched and racketed up the lane out of sight.

Dr Natouche appeared and then Mr Lazenby. The eight passengers stood along the rails and watched the riverbanks take on a new perspective and become remote. Spires and waffle-irons, glass boxes, mansard roofs and the squat cupola of the Norminster Town Hall were now merely there to be stared at with detachment. They shifted about, very slowly, and looked over one another’s shoulders and grew smaller. The Zodiac, now in mid-stream, set her course for Ramsdyke Lock.

“He had been operating,” Alleyn said, “in a very big way in the Middle East. All among the drug barons with one of whom he fell out and who is thought to have grassed on him. From drugs he turned to the Old Master racket and was certainly behind several very big jobs in Paris. Getting certificates for good fakes from galleries and the widows of celebrated painters. He then crossed to New York where he worked off the fruits of this ploy until Interpol began to make interested noises. By the way, it may be noted that at this juncture he had not got beyond a Blue Circular which means of course—”

The boots of the intelligent-looking sandy man in the second row scraped the floor. He made a slight gesture and looked eager.

“I see you know,” Alleyn said.

“Ay, Sir, I do. A Blue International Circular signifies that Interpol cannot place the identity of the creeminal.”

“That’s it. However, they were getting warmer and in 1965 the Jampot found it necessary to transfer to Bolivia where for once he went too far and was put in gaol. Something to do with masquerading in female attire with criminal intent. From there, as I’ve said, he escaped, in May of last year, and sometime later arrived with an efficiently cooked-up passport in a Spanish freighter in England. At that juncture the Yard had no specific charge against him although he featured heavily in the discussions we were holding in San Francisco. He must have already been in touch with the British group he subsequently directed, and one of them booked him in for a late summer cruise in the Zodiac. The object of this manoeuvre will declare itself as we go along.

“At this point I’d like you to take particular note of a disadvantage under which the Jampot laboured. In doing this I am indulging in hindsight. At the time we are speaking about we had no clear indication of what he looked like and our only photograph was a heavily bearded job supplied by the Bolivian police. The ears are hidden by flowing locks, the mouth by a luxuriant moustache and the jaw and chin by rich and carefully tended whiskers.

“We now know, of course, that there was, in his appearance, something that set him apart, that made him physically speaking, an odd man out. Need I,” Alleyn asked, “remind you what this was—?”

The intelligent-looking man seated in the second row made a slight gesture. “Exactly,” Alleyn said and enlarged upon it to the class.

“I’m able,” he went on, “to give you a pretty full account of this apparently blameless little cruise because my wife wrote at some length about it. In her first letter she told me—”