Mr. Hill: If a museum is to show works of great art, it cannot be Fort Knox, nor a high security prison. So whatever the security at a museum, and the state of its alarm system, it will be vulnerable to attack. The best system is a combination of locks, bolts, strengthened glass, CCTV (seeing someone walking around with a balaclava on should be a clue that all is not well, if anyone is watching the monitor) and alarms with good human resources managing them 24 hours a day. That is expensive, and most museums cannot afford that combination, but they should always aspire to it and try to achieve it as best they can, particularly when they have other people's art treasures on loan for an exhibition.

Mr. Hill: These stolen works of art are likely to turn up again because they were stolen in an intelligent way, probably little damaged. But overall, stealing masterpieces is the most stupid thing a thief or thieves can do. They are not readily realisable as cash assets. They are unsaleable on the open market. The values attributed to them, and I read in the Independent this morning here in London that a figure for all of the stolen pictures was put at £250 million. What nonsense.

I also read that they were for some secret collector and his secret collection. More stuff and nonsense. In my experience the only Captain Nemo or Dr. No character I have ever met who collected stolen works of art is George Ortiz of Geneva. He used to show anyone his superb collection of looted antiquities, and every one of his friends and enemies knows what he has got. His main friends are the city fathers of Geneva who are set to inherit it all, and his enemies begin with Lord Renfrew, the famous Emeritus Professor of Archaeology at Cambridge University. Jules Verne and Ian Fleming (actually, Cubby Broccoli) invented all of that secret collector nonsense. These pictures will turn up in drugs raids and other searches over time, unless the police in Rotterdam get a good tip off soon and hit the place where they are stashed now.

Mr. Hill: My view is that this theft was particularly well organised, done quickly and in the almost certain knowledge that the thieves and what they stole would be long gone by the time the police arrived. Also, the thieves were apparently not opportunists such as the two with a ladder at the Van Gogh Museum in Amsterdam some years ago who smashed a window and took the two pictures nearest the broken glass, nor were they Balkan bandits with machine pistols like the ones who hit the Munch Museum in 2004, or the Buhrle Collection in Zurich a few years ago.

The closest pattern I know is of Irish Traveller raids on art in the 1980s through 2010. The pattern in Rotterdam the night before last was closer to that. See the art crimes of The General as he called himself, Martin Cahill of Dublin. Interestingly, one of Cahill's gang, George Mitchell, known as The Penguin, lives close to Rotterdam where he works in commodities with his Colombian, Russian, Dutch, Brit, Irish and other friends. I wonder if he has a part to play in this? He could do something about getting those pictures back, I'm sure, if any good Dutch police officer not in his pay asked him for some help.

What about the Serbian gangs who had been involved in the theft of the two Turners from the Tate Gallery which had been on loan to Frankfurt (as documented in Sandy Nairne's book Art Theft and The Case of the Stolen Turners)? Do you think the paintings, if taken by someone like that Irish gangs, would be shipped into Britain? If you were to steal these paintings from Rotterdam, what country would you ship them to?