‘But then there is no crime,’ his wife declared.

‘Precisely,’ he said. ‘No crime… and yet a crime. If the body’s never found, damned hard to convict anyone. Or if something’s stolen, but never noticed. See what I’m getting at?’

I did, of course, and perhaps you do, too.

The Tate, like every other gallery I can think of, has considerably less wall-space than it has works in its collection. These days, we do not like to cram our paintings together (though when well done, the effect can be breathtaking). One large canvas may have a whole wall to iself, and praise be that Bacon’s triptychs did not start a revolution, or there’d be precious little work on display in our galleries of modern art. For every display of gigantism, it is blessed relief, is it not, to turn to a miniaturist? Not that there are many miniatures in the Tate’s storerooms. I was there with an acquaintance of mine, the dealer Gregory Jance.

Jance worked out of Zurich for years, for no other reason, according to interviews, than that ‘they couldn’t touch me there’. There had always been rumours about him, rumours which started to make sense when one attempted to balance his few premier-league sales (and therefore commissions) against his lavish lifestyle. These days, he had homes in Belgravia, Manhattan’s Upper East Side, and Moscow, as well as a sprawling compound on the outskirts of Zurich. The Moscow home seemed curious until one recalled stories of ikons smuggled out of the old Soviet Union and of art treasures taken from the Nazis, treasures which had ended up in the hands of Politburo chiefs desperate for such things as hard dollars and new passports.

Yes, if even half the tales were true, then Gregory Jance had sailed pretty close to the wind. I was counting on it.

‘What a waste,’ he said, as I gave him a short tour of the storerooms. The place was cool and hushed, except for the occasional click of the machines which monitored air temperature, light and humidity. On the walls of the Tate proper, paintings such as those we passed now would be pored over, passed by with reverence. Here, they were stacked one against the other, most shrouded in white sheeting like corpses or Hamlet’s ghost in some shoddy student production. Identifier tags hung from the sheets like so many items in a lost property office.

‘Such a waste,’ Jance sighed, with just a touch of melodrama. His dress sense did not lack drama either: crumpled cream linen suit, white brogues, screaming red shirt and white silk cravat. He shuffled along like an old man, running the rim of his panama hat through his fingers. It was a nice performance, but if I knew my man, then beneath it he was like bronze.

Our meeting – en principe – was to discuss his latest crop of ‘world-renowned artists’. Like most other gallery owners – those who act as agents for certain artists – Jance was keen to sell to the Tate, or to any other ‘national’ gallery. He wanted the price hike that came with it, along with the kudos. But mostly the price hike.

He had polaroids and slides with him. In my office, I placed the slides on a lightbox and took my magnifier to them. A pitiful array of semi-talent dulled my eyes and my senses. Huge graffiti-style whorls which had been ‘in’ the previous summer in New York (mainly, in my view, because the practitioners tended to die young). Some neo-cubist stuff by a Swiss artist whose previous work was familiar to me. He had been growing in stature, but this present direction seemed to me an alley with a brick wall at the end, and I told Jance as much. At least he had a nice sense of colour and juxtaposition. But there was worse to come: combine paintings which Rauschenberg could have constructed in kindergarten; some not very clever geometric paintings, too clearly based on Stella’s ‘Protractor’ series; and ‘found’ sculptures which looked like Nam June Paik on a very bad day.

Throughout, Jance was giving me his pitch, though without much enthusiasm. Where did he collect these people? (The unkind said he sought out the least popular exhibits at art school graduation shows.) More to the point, where did he sell them? I hadn’t heard of him making any impact at all as an agent. What money he made, he seemed to make by other means.

Finally, he lifted a handful of polaroids from his pocket. ‘My latest find,’ he confided. ‘Scottish. Great future.’

I looked through them. ‘How old?’

He shrugged. ‘Twenty-six, twenty-seven.’

I deducted five or six years and handed the photos back. ‘Gregory,’ I said, ‘she’s still at college. These are derivative – evidence she’s learning from those who have gone before – and stylised, such as students often produce. She has talent, and I like the humour, even if that too is borrowed from other Scottish artists.’

He seemed to be looking in vain for the humour in the photos.

‘Bruce McLean,’ I said helpfully, ‘Paolozzi, John Bellany’s fish. Look closely and you’ll see.’ I paused. ‘Bring her back in five or ten years, if she’s kept hard at it, if she’s matured, and if she has that nose for the difference between genius and sham…’

He pocketed the photos and gathered up his slides, his eyes glinting as though there might be some moisture there.

‘You’re a hard man,’ he told me.

‘But a fair one, I hope. And to prove it, let me buy you a drink.’

I didn’t put my proposition to him quite then, of course, not over coffee and sticky cakes in the Tate cafeteria. We met a few weeks later – casually as it were. We dined at a small place in a part of town neither of us frequented. I asked him about his young coterie of artists. They seemed, I said, quite skilled in impersonation.

‘Impersonation?’

‘They have studied the greats,’ I explained, ‘and can reproduce them with a fair degree of skill.’

‘Reproduce them,’ he echoed quietly.

‘Reproduce them,’ I said. ‘I mean, the influences are there.’ I paused. ‘I’m not saying they copy.’

‘No, not that.’ Jance looked up from his untouched food. ‘Are you coming to some point?’

I smiled. ‘A lot of paintings in the storerooms, Gregory. They so seldom see the light of day.’

‘Yes, pity, that. Such a waste.’

‘When people could be savouring them.’

He nodded, poured some wine for both of us. ‘I think I begin to see,’ he said. ‘I think I begin to see.’

That was the start of our little enterprise. You know what it was, of course. You have a keen mind. You are shrewd and discerning. Perhaps you pride yourself on these things, on always being one step ahead, on knowing things before those around you have perceived them. Perhaps you, too, think yourself capable of the perfect crime, a crime where there is no crime.

There was no crime, because nothing was missing from the quarterly inventory. First, I would photograph the work. Indeed, on a couple of occasions, I even took one of Jance’s young artists down to the storeroom and showed her the painting she’d be copying. She’d been chosen because she had studied the minimalists, and this was to be a minimalist commission.

Minimalism, interestingly, proved the most difficult style to reproduce faithfully. In a busy picture, there’s so much to look at that one can miss a wrong shade or the fingers of a hand which have failed to curl to the right degree. But with a couple of black lines and some pink waves… well, fakes were easier to spot. So it was that Jance’s artist saw the work she was to replicate face to face. Then we did the measurements, took the polaroids, and she drew some preliminary sketches. Jance was in charge of finding the right quality of canvas, the correct frame. My job was to remove the real canvas, smuggle it from the gallery, and replace it with the copy, reframing the finished work afterwards.

We were judicious, Jance and I. We chose our works with care. One or two a year – we never got greedy. The choice would depend on a combination of factors. We didn’t want artists who were too well known, but we wanted them dead if possible. (I had a fear of an artist coming to inspect his work at the Tate and finding a copy instead.) There had to be a buyer – a private collector, who would keep the work private. We couldn’t have a painting being loaned to some collection or exhibition when it was supposed to be safely tucked away in the vaults of the Tate. Thankfully, as I’d expected, Jance seemed to know his market. We never had any problems on that score. But there was another factor. Every now and then, there would be requests from exhibitions for the loan of a painting – one we’d copied. But as curator, I would find reasons why the work in question had to remain at the Tate, and might offer, by way of consolation, some other work instead.