‘But I understand that there were seven separate numerals.’

‘I have an excellent memory.’

‘Then I will ask you this. Were the numbers selected by you? Did they perhaps have some reference to events in your life? Your date of birth, for example, or that of your wife?’

‘Absolutely not. The safe arrived with the combination integrated. And before you ask, Sentry have their own security protocols. Nobody in the company knew which safe had been sold to me or where it was going to be installed. It had come all the way from America on a container ship. I had workmen pick it up in Southampton and bring it to my London home. The combination was sent to me by post a few days later.’

‘Thank you. Please continue.’

Charles Pargeter took a breath. He was not the sort of man who was used to asking favours. In his business, he would issue instructions and expect them to be followed to the letter. Pünd got the impression that he had rehearsed what he was about to say.

‘I bought the Ludendorff Diamond for many reasons,’ he said. ‘It is an object of great beauty which could be more than a billion years old. Think of that! It is unique. It is also, strangely enough, a wise investment. And if I’m going to be honest with you, Mr Pünd, there may have been an element of vanity in my decision. When you have been fortunate enough to amass a great deal of wealth, there is always the temptation to make a statement, not to the general public but to yourself. To remind yourself of your own success.

‘So when I tell you that I have been hurt by the theft, I mean it in every sense. Whoever took the diamond has made a fool out of me. I have always been fond of the British and frankly, following this incident, I’ve been surprised how quickly they seem to have taken against me. There was even a cartoon of me in Punch magazine. You may have seen it.’

Pünd made a gesture to suggest that he hadn’t, although in fact he remembered it well. It had shown the multimillionaire sitting at the breakfast table in his pyjamas, eating a boiled egg with the diamond concealed inside the shell. The caption underneath read: ‘Now, why didn’t I look there?’

‘It’s even been suggested that I myself was involved in the robbery,’ Pargeter continued. ‘An accusation that’s as absurd as it’s damaging. In short, I’m being humiliated all over the country, and frankly, I find this almost as hard to bear as the loss of the jewel itself. So let me get to the point. I will pay you any money you demand to investigate what actually happened. Who did it and how it was done. If you are able to return my property to me, I will pay you a bonus of fifty thousand pounds. Forgive me for being so direct, Mr Pünd. I’m sure you’re a busy man, so let me know what you think and I won’t waste any more of your time.’

In fact, Pünd had made his decision the moment Pargeter walked into the room. He was intrigued. This was one of those very rare examples of a crime committed without violence that could, perhaps, be approached purely as an intellectual challenge. The timing, also, was fortuitous. The lease on his flat and office was about to expire. He had been looking for somewhere new to live and had found a flat in Farringdon that seemed ideal except that it was well out of his price range. Pünd did not believe in fate or destiny. But Charles Pargeter might have been sent in answer to his prayers.

He went round to Knightsbridge the next day, driven by Pargeter’s chauffeur, who had picked him up in a silver Rolls-Royce. The house was in one of the quiet streets behind Harrods department store. It was unusual in that it stood alone, surrounded by a low brick wall with a gravel drive and flower beds. Pünd began with the broken window, which was round the side of the house. Already, that puzzled him. It did not fit in with what he had read in the papers and what he had been told. He was shown in through the front door to find Charles Pargeter and his wife waiting for him. She was an extremely elegant woman, taller than her husband, dressed simply in a cashmere jersey and slacks. She had no jewellery. The house itself was quite ordinary. As far as Pünd could see, there were no masterpieces on the walls, no priceless silver on display. Perhaps the Pargeters’ home in New York was more ostentatious.

‘Would you like some coffee, Mr Pünd?’ Elaine Pargeter asked. ‘We can go into the drawing room … ’

‘I would prefer to begin upstairs, if you don’t mind, Mrs Pargeter. To start with, I would like to see this safe that was, according to its makers … impregnable. Is that the word?’

‘I’ll take you there,’ Charles Pargeter said.

As they climbed the stairs, Pünd raised the question that had occurred to him outside. ‘I am puzzled,’ he said. ‘You arrived, quite late, from the party on the night that the robbery took place.’

‘Yes. It was about one o’clock.’

‘There were three of you.’

‘Yes. John Berkeley is an old friend of mine. He’s a vice president with Shell Transport and Trading. We were actually at college together. He happened to be in London for a few days and he usually stays with us. Saves paying out for a hotel.’

‘Which one of you saw that the window had been broken? It seems to me that walking from the car to the front door, you would not have had a view of the side of the house.’

‘Actually, that was me,’ Elaine Pargeter explained. ‘John saw fragments of glass on the drive. They were reflecting the moon. I went round to investigate and that was when I saw the window was broken.’

‘Did you go straight upstairs?’

‘I wanted Elaine to stay in the car,’ Pargeter said. ‘I was afraid there might be intruders in the house and I didn’t want to put her in harm’s way—’

‘I wasn’t having any of that!’ Elaine exclaimed.

‘That’s right. So the three of us went in together. I saw that the alarms were off and that told me something was wrong. We have a butler, Harris, and he’d have been asleep in the servants’ wing, but even so the alarms should have been on in the main house. We went straight to the master bedroom. I knew that everything that was valuable to me, and that includes the diamond, of course, was in the safe. I remember putting my hand in my pocket and feeling my key. It never occurred to me that the safe could have been opened.’

They had reached the top of the stairs and crossed the corridor, entering a room decorated in a vaguely Chinese style with dark red wallpaper and views over the back garden. As with the rest of the house, the most impressive thing about the bedroom was its size. The bed was huge, the curtains theatrical, the dressing table antique. One door led into a bathroom. The other opened into a narrow corridor with wardrobes on either side. After about ten feet, the wardrobes stopped and there was a small alcove with a domed ceiling. It could have been purpose-built for the safe that stood there with its back against the far wall.

If the millionaire and his wife had expected Pünd to move forward and examine the safe, they were disappointed. He stood where he was, half frowning, as if he was trying to sense the atmosphere. Finally, he spoke. ‘Did you turn the lights on when you came into the room?’ he asked.

‘In the bedroom. Yes. But not in the walk-in closet.’

‘And why was that?’

‘We didn’t want to leave footmarks or fingerprints. But I can tell you, there was enough light for us to see everything. The safe door was open and the inside was clearly empty. I have to say that I was very glad to have John Berkeley with me right then. I’m not an emotional man. I guess I’m used to keeping things damped down. But I felt sick. I thought I was going to faint. I stand by what I said to you yesterday, Mr Pünd, but right then I was thinking about how much had been taken from me. I had lost millions and millions of dollars and at the same time it was impossible. I was holding the only key to the safe, goddamn it! I had it right in my hand.’

‘So what did you do then?’

‘Obviously, I couldn’t go into the room. It was a crime scene. I didn’t want to disturb any possible evidence.’

‘That is very sensible.’

‘John took control of the situation. He got Elaine to call the police while he took me downstairs and gave me a large Scotch. He also got Harris out of bed and asked him if he’d heard anything, but there was no joy there. The truth is, Harris is much too old for the job, but he’s been with me so long I don’t have the heart to get rid of him. I just keep hoping he’ll retire.’

‘And you trust him?’

‘He’s been with us for thirty years, Mr Pünd. When he does finally go, we’ll look after him. He knows that. And what’s a man of his age going to do with a diamond like that? It’s inconceivable he had anything to do with it.’