Anyone planning to view The Last Supper at Magdalen College this Good Friday will be disappointed, since the painting was removed at the end of last year to become part of the Leonardo exhibition at the National Gallery, London (and subsequently at a show in Madrid). It will not be back in its place, high in the college ante chapel, until May 23.

It belongs to the Royal Academy but is on long-term loan to the college. Ever since its arrival in Oxford in September 1992, stretched on a vast metal drum and packed into a specially constructed wooden crate with 20 people in attendance, it has been attracting a steadily increasing number of visitors, some returning time after time. Such is the magnetic draw of Leonardo.

Not that this painting is by Leonardo da Vinci, though it is of momentous importance all the same. It is by the Lombard artist Giovan Pietro Rizzoli, known as Giampietrino (active 1495-1549). He was a pupil of Leonardo who, luckily for posterity, copied on to canvas the original work — the fresco in the refectory of the Milan monastery of Santa Maria delle Grazie — a few years after it was completed in 1498.

Luckily, I say, because the original did not survive the ravages of time well. This picture, therefore, became an essential crib for art experts restoring the original at the end of the 20th century; sadly, it had not only suffered through time but also thanks to Napoleon’s troops throwing unsavory things at it during their occupation of Milan, and also thanks to a stray Allied bomb hitting the monastery during the Second World War, thereby leaving the fresco for a time open to the elements.

As if that were not bad enough, there were the alterations perpetrated by the monks of Santa Maria delle Grazie too. At some stage, they evidently installed a door beneath the fresco, obliterating Christ’s feet in the process. So, all in all, thank God for Giampietrino (even though a fairly acrimonious debate still rumbles on among art experts about how true to his copy the restoration of the original fresco has been).

Magdalen was truly grateful to receive the painting, with the then President of the college, Anthony Smith, declaring: “Word rapidly passed through the college and through Oxford generally, and ever since that moment there has been a steady trickle of visitors, some returning again and again, to view the work which Sir Ernst Gombrich described as ‘one of the great miracles wrought by human genius’.”

The great Austrian-born art historian E.H. Gombrich (1909-2001) was at the installation ceremony in March 1993 and lectured to a packed ante-chapel, after which the Bishop of Winchester (Visitor to the College) blessed the painting and the choir sang an anthem composed for the occasion.

Interestingly, Sir Ernst began by saying how much Leonardo would probably have disapproved of his talk. He began: “It is unlikely that Leonardo would have approved of my attempts to talk about his work or its copy. After all, he was the author of the so-called Paragone, the comparison or rather the contest of the various forms of art.”

He reminded the audience that Leonardo wrote: “Your pen will be worn out before you have fully described something that the painter may present to you instantaneously using his science. And your tongue will be impeded by thirst and your body by sleep and hunger, before you could show in words what the painter may show in an instant.”

Leonardo chose the Last Supper story according to St John despite the fact that, unlike the story according to the other three gospels, it does not mention the Eucharist. What he portrays instead is the moment after he has said “Verily, verily I say unto you that one of you shall betray me.” And the 12 diners (in addition to Christ) looked at one another “and began to be sorrowful, and to say unto Him, Is it I?” And Judas Iscariot knocked over the salt!

The Ante-Chapel in which the Giampietrino picture hangs dates from about the same time as the painting, though it was much altered just before Victoria’s accession to the throne by Lewis Cottingham (1787- 1847). But anyone wanting to see a really Victorian version of the Last Supper could do worse than visit the Church of St Thomas of Canterbury in Elsfield. Inside they will find the newly-restored mosaic of the subject as translated by Antonio Salviati (1816-1890), who had perfected a way of mass-producing mosaic tiles. Obviously based on Leonardo’s fresco, the mosaic nevertheless has a chalice in front of Christ rather than the everyday crockery that the monks of Santa Maria delle Grazie would have recognised.