This mighty building sits a few hundred metres from the roar of the A47, but it has a presence about it that soon makes you forget the noise of traffic. There is no village, no houses at all nearby, just this huge fortress sitting in the fields. Pretty much everything you see post-dates the Black Death. The tower is the earliest part, from just before 1400, and then a sequence of bequests leads to the nave, chancel and internal furnishings that are finished by the early 16th century. This is the English Church at the height of its late medieval glory. Because there is no clerestory, no aisles, and everything is to scale, it is difficult to really get an impression from the photographs above of quite how vast St Mary is. Look at the top picture; I am six feet tall, and when I stood beside the porch, my head didn't come quite up to the top of the lower windows. English churches naturally have an air of permanence, but this building is positively bullish about its intention to sit here for all eternity, and longer if possible.

But East Anglia has loads of big churches, so what makes North Tuddenham special? Well, there's nowhere quite like it. We expected to have to get a key, but as we approached the building we could hear sad organ music playing. I tried the door, and it was open. We stepped inside, into a temperature a good five degrees colder than the winter air outside.

It was like entering a cathedral. As our breath clouded the air, I looked eastward towards the vast mouth of the chancel arch into what is nothing less than a Victorian citadel.

The walls, to a height of six feet or more, are covered in vivid patterned tiles. Beyond them, rising to the high roof, is elaborate stencilling. This happened to many churches, especially big ones, but by the 1960s and 1970s, when enthusiasm for Victorian styles was at its nadir, they were being removed and destroyed in vast quantities. Even here, they were painted over, but a change of heart has revealed them to the light of day again. High above, huge pastel roundels depict angels and Saints. This is seen at its most complete in the chancel, which could so easily be some 19th century Anglo-catholic temple in London, Buenos Aires or Calcutta. In the nave, the huge windows are filled with Ward & Hughes glass, but the upper lights have a wonderful collection of glass from the 14th and 15th centuries.

Two consecutive Rectors left their indelible mark on St Mary. They were Robert Barry and Benjamin Armstrong, who between them shepherded the parish from 1851 to 1924. As we know, the vast majority of parish churches were restored to their medieval configuration by the Victorians after centuries as preaching houses, but few churches retain quite so much evidence of this as St Mary.

The story goes that Barry found the medieval glass in a builder's yard in nearby Dereham in the early 1880s. There are ideas about where it came from; half a century later, surviving members of the Armstrong family recalled Barry mentioning Billingford, near North Elmham, or perhaps Elsing. Neither is likely, and perhaps we will never know. There are parts of several sequences, most notably the life and martyrdoms of St Margaret and St George, the Seven Sacraments, the Apostles with Creed scrolls, and, most unusually, incidents in the teaching life of Christ. The best is probably in the west window, but there are also figures in the upper lights of the north aisle and in some of the south aisle. Fragments of other pieces are in the porch windows, and what couldn't be fitted in here was given to nearby Welbourne, where it can still be seen in the porch windows there.

In the west window are two panels depicting incidents early in the St Margaret story. In the first she sits in a field and spins, and in the second we see her for the first time in her suitor's palace. St Margaret was a hugely important Saint in medieval East Anglia. A large proportion of the churches in England dedicated to her are in Norfolk and Suffolk. Part of another sequence of her life and martyrdom survives at Combs in Suffolk, and there is a record of another at Heydon, now lost. The third panel in the lower west window depicts two incidents in the St George story, his donning of his armour and his attacking the dragon.

Images from the martyrdoms, as well as from the other sequences, can be seen below. Hover for a caption, and click on them to see them enlarged.

As I photographed the glass, Peter chatted to the nice man who had been playing the organ. The temperature inside this vast barn was not much more than freezing, and so he had huddled by one of the heaters in the chancel to practice the hymns for Sunday. I wondered how on earth they kept this place warm in winter, but as the man pointed out, their congregation was only six or seven, and so they didn't use the nave anymore.

Even in the chancel, they must rattle around. This church would seat seven or eight hundred people quite comfortably, and it is extraordinary to think that barely a hundredth of this number use it regularly now. The man said that they would keep the church going as long as they could, but of course it must never be lost to us, because it is a national treasure. And it isn't only the glass. The screen, which probably did come from here, retains panel paintings from the first decades of the 16th century, shortly before the Reformation.

There are twelve panels, but only the middle eight have figures. They are St Agnes, St Gregory, St Dorothy and St Jeron on the north side, and St Catherine, St Sebastian, St Etheldreda and St Roche on the south side. St Agnes has a dagger pointed at her neck and her lamb at her foot. St Dorothy has flowers and fruit, while St Jeron has a falcon on his arm. St Catherine holds her sword and wheel, St Sebastian an arrow and St Roche points at the plague sores on his leg as at Stalham.

There are more panels from a dado built into the tower arch screen. Mortlock records that these were bought by Barry from 'a lumber shop'. They depict two of the four evangelists, Matthew and Mark, and two of the four Latin doctors, Gregory and Augustine. I wonder where the other four are?

As the Church of England slowly retreats into managed decline, buildings like this are a huge burden. What is the future for it?

St Mary is an important historical document, but it is more than that. It is a monument to taste, the fashionable passions of the late 19th and early 20th centuries. Many of the elements that make it up are medieval,certainly, but what you see here is a coherent testimony to a late Victorian vision of what the Middle Ages had been like, to a time in the life of the Church of England that has now slipped just out of reach. There is grandeur, to be sure; but it is the triumph of a lost age. Even if you were not interested particularly in the 15th and early 16th centuries, this would be a place to come, if only to sense the ghosts of militant Victorian Anglo-catholicism.

But there is even more. For, as I stood there, I felt a quiet sadness come dropping slowly through the icy air. This is a tremendous place, and it is still loved; but the church that Barry and Armstrong created is dying, finally reaching the end of its liturgical and artistic life. It has been left out on the end of an event, having survived it; but now hardly anyone remains to celebrate it. There will never be an another Anglo-catholic revival in the Church of England, and soon only buildings like this will remind us of it, precious evidence of that extraordinary time.

Simon Knott, February 2006