When I first visited St Mary Magdalene about ten years ago, I was surprised and pleased to see a sign down at the roadside telling me that the church was open. At the time, I had visited several hundred Suffolk churches, and although I had found most of them open, this was the first time I'd come across a church openly advertising the fact. Because of this, I described St Mary Magdalene as one of the most welcoming churches in Suffolk, and observed that, since nearby St Mary at Thornham Parva was one of the others, it might have been due to something in the water round here. More likely, it reflected the philanthropy and generosity of the Henniker family, of nearby Thornham Hall. This is the Henniker church. If you walk westwards of the tower, you will see Thornham Hall over the fence, across a field. You will also find yourself standing among the Henniker graves, which are as understated and restrained as the Hall itself

Since that visit, I have been to about 1,500 churches in the eastern counties, and during the course of that time something rather interesting has happened. I have seen signs like the one here increasingly frequently, sometimes at churches I had previously visited and even found locked. Some churches go even further: in the last couple of months, I have visited no less than three open churches where the visitor has been invited to make a cup of tea or coffee, and have a biscuit or a piece of cake from the tin. It almost seems as if they are competing to be the most hospitable.

Certainly in Suffolk, there has been a change in attiude and emphasis over the last decade. More and more churches are following the example of Thornham Magna because they see their mission as one to all the people of God, and not just to the Sunday club. Increasingly, the Church of England has offered itself as a place for private prayer and meditation. Ironically, perhaps, this is at a time when fewer and fewer people are likely to unthinkingly put down C of E on a form which asks for their religion. Some Dioceses, St Edmundsbury and Ipswich included, fully realise that open churches are the greatest single act of witness that they have.

The good people of Thornham Magna have always realised this, and perhaps 70% of the parish churches of Suffolk are now open every day. And yet, and yet... there are still locked churches I visit where no welcoming keyholder notice is displayed. When I eventually track down the key, I am often told that We have to keep it locked because there's no one to be on duty... all churches are kept locked these days. When I disabuse people of this notion they are often very surprised, and I suppose that often they don't really believe me. Only twice in those 1,500 churches have I ever been refused admittance to a church, and on four other occasions the key was handed out grudgingly. A tiny fraction, then, and yet it made me very grumpy at the time. For, of course, protection of property and suspicion of strangers are not Gospel values. I suspect that the real reason for many of the locked churches, and there are still several hundred, is sheer inertia on the part of the churchwardens concerned. But they are very much a minority.

But you need not worry about any of this if you visit Thornham Magna. This is a lovely part of Suffolk, perhaps most familiar for the Thornham Walks in woods around the church, and for the decent pub down on the Eye road. The church is attractively set above the lane on a cushion of green and brown, although the 14th century tower is rather forbidding, not least because of the flat effect of the east wall caused by the buttresses being flush with it. Something similar exists at Rendlesham.

The porch is very elaborate, with its three alcoves. These, presumably, would have contained a rood group before the Anglican reformers removed them in the 16th century. The porch doesn't predate the Reformation by much - and notice the way it abuts the window! Sometimes, these 15th century architects weren't all they're cracked up to be.

You enter what is inevitably a rather dark church, thanks to the few windows and ranges of coloured glass. St Mary Magdalene has none of the treasures of Thornham Parva, but it is a delight nonetheless. The Hennikers have their memorials here, and what a contrast they are to the triumphalism of the Tollemaches at Helmingham or the Poleys at Boxted. The best of them is to Edward Henniker, who died in 1902. It is the window in the south-west of the nave, and features glass by Morris & Co. The figures are by Edward Burne-Jones, and depict a gorgeous St Mary Magdalene, a mournful St John and the rather sombre Blessed Virgin at the foot of the cross. Along with glass at Shimpling and Hopton, it is one of the best Pre-Raphaelite windows in Suffolk.

Another of the memorials on this wall is by William Woodington, who, Sam Mortlock tells us, was responsible for the bronze reliefs around the base of Nelson's Column. Even more striking in the nave are the seven hatchments, an unusually large number even for Suffolk, which, I am told, has more than any other county apart from Kent.

The gloved hand of lukewarm ritualism fell heavily here in the 19th century, and not much that is medieval survived. The hammerbeam roof just about qualifies (that in the chancel is 19th century) and there is a gorgeous piscina south of the sanctuary. Also in the sanctuary is the Henniker's one attempt at full-blown triumphalism, the memorial to John Henniker Major. Faith clasps the urn looking downcast, while Hope looks up, resting against her anchor, a characterful face at once sorrowful and earnest.

The Henniker memorials are an interesting history of the colonial adventures of an established landed family. There are frequent mentions of foreign places - one was killed in Spain, in the Battle of Almanza, while another served in the Egyptian Campaign... and throughout the South African War. But my favourite is a simple one to Martha Catherine Henniker, who was born in July 1838 and died just three months later. The Tender Plant shed forth its beauteous form, Look'd round upon this boisterous world, found its chilling blasts too rough, droop'd its head and died. Isn't that lovely? I wonder if it can have been a comfort. It is signed CRH, perhaps her mother or father. As I left, the grieving figures in the Burne-Jones window seemed to reflect something of the sadness in Martha Catherine Henniker's inscription.