Mark Alexander has never lacked ambition. I’ve known this since I suggested back in the early ’90s he fund his remarkable painting talent by going to art school and he decided Oxford University’s Ruskin School fitted the bill. He didn’t regard having just the two ‘O’ Levels as an insuperable obstacle.

Of course, he got in – an achievement that was reported by the Daily Mirror as if they’d discovered a latter-day and rather happier Jude the Obscure (I think their headline was something like ‘Factory Worker Goes to Oxford’). It wasn’t a fluke: he got a First, even in his art history paper. And he’s not lacked ambition since, his work being exhibited in London, Basel and Berlin and appearing in some of the world’s most prestigious collections.

So it came as no surprise to find myself at a private view yesterday evening talking to him under the dome of St Paul’s Cathedral whilst admiring his two latest works – together The Red Mannheim (below and bottom), two non-identical twin, four metre-high paintings in a red monochrome palate. They each feature an image of the ruined Mannheim Altarpiece, a masterpiece of rococo carved from limewood in 1739-41 by Paul Egell, probably the outstanding German sculptor of his age. They do much more than hold their own in this impressive setting.

Mark’s work is difficult but perhaps not just in the sense often intended by contemporary art critics. That is, it’s difficult to make, often involving craft techniques and skills that are little different from those used by the Old Masters. His sometimes staggering technical virtuosity doesn’t, however, preclude his works from being as conceptual and philosophic, and sometimes as playful, as anything more obviously contemporary. A remarkably successful attempt to make a flat, painted surface resemble beaten Aztec gold comes to mind. His latest work is no exception

How the Mannheim Altarpiece came to be ruined is still partly mysterious. Mark used to visit it regularly in Berlin’s Bode Museum – he lived in the city for a number of years and a friend of his, a German master-carver who sometimes makes his frames, was helping to restore the base. His fascination eventually impelled him to consult the museum’s curators. In his words:

During the Second World War it was thought that for safekeeping a number of the most valuable German artworks should be stored in the Friedrichshain bunker. But towards the end of the war, in the confusion of the Soviet advance, there was a fire after which many of the works were lost. It may have been started by an air raid or perhaps by some Red Army troops. We also still don’t know for sure whether the items were destroyed in the flames or taken and never returned by the Russians.

In the case of the Altarpiece, originally there was much more to it: Christ on his cross, palm trees, attendant figures including the Virgin Mary, Mary Magdalene. These had been removed and stored separately – but were they consumed in the fire or were they spirited away by the Russians, not being sent back unlike the damaged backing and surround that’s all we have left on view in the Bode Museum?

The Mannheim Altarpiece, then, was a victim of the war, making its presence in St Paul’s this year, the anniversary of the 1940 Blitz, appropriate and even resonant. St Paul’s is a famous survivor of the conflict: “At all costs, St Paul’s must be saved,” believed Churchill. And saved it was, the image (below) immediately becoming an icon of national survival and defiance. The contrasting fate of the altarpiece makes for an interesting juxtaposition – even if it too survived, albeit as a fire-damaged fragment.

Mark’s work is displayed as part of St Paul’s Art Programme, which also features artists such as Anthony Gormley and Bill Viola. It ’seeks to explore the encounter between art and faith’. But The Red Mannheim’s relationship to religious faith – certainly the Christian faith – is surprisingly oblique, even subversive, particularly given the source of its image and its current home. Mark:

When I first saw the altarpiece in Berlin religion wasn’t on my mind. I was more interested in how it’s elaborate rococo had been mostly erased leaving some sort of sexual negative, really an image of pagan sexuality. In the Bode Museum in Berlin the altarpiece is hung so that it seems to float on the wall, an ever-ascending icon. It seemed to be an extremely primitive scene. Christ had gone, and taken his cross and mourners with him. The only figures left were the distraught cherubs in the bottom corner – representing Adam and Eve. So in a way all we’re left with is Original Sin, a black hole and this phallic negative.

The allegorical significance doesn’t need spelling out. So is the red an accentuation of this sort of latent sexuality?

I got the colour from the Pina Bausch production of Stravinsky’s Rite of Spring, which I saw last year or the year before at Sadlers Wells. The dancers came on wearing some sort of absorbent, flimsy pink material. As they perspired the pink was saturated into red and it ended up sopping, clinging. It was incredibly sexual. I think I’ve managed to replicate that colour in the Red Mannheim. God had left the building.

And you can get a sense of what was left after ‘God had left the building’ from this review of the 2008 production:

On a stage covered in tons of peat, 16 women and 16 men carve their ritual sacrifice out of the weight and duty of Bausch’s frighteningly visceral choreography. It’s rare to see her dancers in unison – especially on such a scale – and the impact is absolutely thrilling.

The sexual overtones are threatening and driven by biological instinct: the men are predators, the women are prey and the fear of rape is their unspoken bond

Sex and violence. I wonder whether the St Paul’s authorities are entirely comfortable with this reading of the work? But it’s not all sex and violence. Mark again:

I also like the red as it corresponds to the story of the Mannheim – I wanted to represent this ambiguity in the red – sometimes it represents the flames, sometimes it might be the Red Army.

Probably more political than it seems at first blush, too.

Like a lot of Mark’s work The Red Mannheim resists being encapsulated in a few neat, summary phrases. It transcends the often trite conceptual gimmicks, the unamusing punch-lines, the hackneyed philosophy of too much contemporary art. It’s layered, referential, allusive and resonant. The critic Craig Raine, a long-time supporter of Mark’s, was at the private view, his presence emblematic of the almost literary qualities of Mark’s work, I wonder

But even if you knew nothing about The Red Mannheim’s history or its creation you would still surely be struck by both its power and its delicacy: the scarlets, crimsons and charcoals are redolent of heat, sexual, diabolic or restoratively warming to taste. One also senses the lick of flames, kindling, consuming and charring. The odd drip of black paint suggests it might be melting.

It evokes more than an ultimately destructive heat, however. Its vividness in parts is lively, literally so: it’s the bright blood of childbirth or the softer glow of embryonic flesh illuminated by the probing camera of a thousand TV documentaries. And it’s inevitable that a palate of reds and blacks, by turns vivid and sombre, will communicate diverse emotions: rage, desire, despair and even hope.

It’s hardly an entirely reassuring work. But it’s one with a subject that despite being literally charred and ruined is nevertheless infused with life and energy. It’s a remarkable transformation, as Mark suggests:

I think it looks more powerful now than when it was this rather cute rococo work. What’s happened to it has made it more powerful, more primitive. It’s interesting how history and time act on things – the altarpiece in this way is a palimpsest. Through the disasters of the 20th century we can still see the 18th century and, I think, a lot more than that.