As I am forever mentioning in this column, you may kid yourself that you know your own county well, interior and coast. You may then stand be-monocled by your fireplace in your smoking jacket, brandy glass in hand, cigarette holder gripped between your teeth and imagine yourself to be a very fine fellow indeed.

And then, suddenly, perhaps as a result of an idle conversation, you’ll realise that you’ve missed a large bit of the county’s jigsaw out and that you’ll have to start all over again.

I had never been to the Dengie Peninsula before. Nor had I ever seen St Peter’s Chapel, at Bradwell-on-Sea, supposedly the oldest church in Britain. Nothing would do, my companion said, but that we must go and see it – just as soon as the sleet from all this climate change we’d been experiencing had abated.

St Peter’s Chapel was founded by St Cedd, who brought Christianity to the East Saxons in AD 654. It was built on – and partly out of – the remains of an old Roman fort constructed round about AD 200. The footpath to it, she said, still had little fragments of Roman pottery in it. She added that inside the building, it was highly atmospheric, very tranquil and that I would almost certainly like it.

Now, the Dengie peninsula is beautiful and very strange. Bradwell-on-Sea is about a mile from the water – which isn’t really the sea at all but the Blackwater estuary.

St Peter’s Chapel doesn’t look like a church, it resembles a stone barn. This is probably because, after falling out of use as a church, for many years it actually was used as a barn. Then, in 1920 it was re-discovered, restored and pressed back into service as a place of worship.

During the last war, it’s also said, the building was earmarked for demolition by the RAF who were busy flattening inconvenient landmarks – until a gimlet-eyed officer realised that it was in fact an ancient church and one of the holiest places in Europe.

Unfortunately, I was in a particularly stupid mood that day. On the way to see St Cedd’s ancient chapel, I noticed a roadsign.

It pointed the way to The Marshes. “That would be Richard and Valerie Marsh.” I said to my chauffeuse. “An ordinary Essex couple. He’s smoking a pipe and and doing a bit of DIY and she’s knocking up lunch at the gas stove – except that there’s probably no actual house, just a husband and wife performing domestic chores in the middle of a field.”

This set the tone for the rest of the trip. Later, in St Peter’s Chapel itself, a fine and awe-inspiring example of early Christian simplicity, when asked if I’d noticed anything, I replied. “Yeah. It’s freezing. Can we go for lunch now, please?”

Outside the chapel, in strong February sunlight, any of its heat cancelled out by a character-forming north-westerly gale, I observed a well-maintained shed standing next to the church. “That’ll be where they keep the heaters locked up, then.” I said. “Gas Super Sers, probably.”

Finally, walking back up the path towards Bradwell, I saw The Sandal. At this point any last skeins of gravitas in me unravelled completely. In the wet grass beside the track was a single abandoned sandal, of a type made of recycled materials, often found advertised in back page adverts of the more liberal-minded broadsheets.

“It is the sacred solitary sandal of St Cedd’s.” I cried. “ And lo, a pilgrim from a faraway land, being weary and cold and having broken his recycled sandal, lost heart and was thereby condemned to wander the Dengie Peninsula for 40 days in search of a pub that was still serving lunch after say, 1.49pm. And yet, found he none” We left.

In a Maldon pub, later that afternoon, whilst leafing through an old guidebook about Dengie I remembered seeing the villages of Tillingham and Bradwell, which possess the most incredible traditional Essex weatherboarded cottages.

The villages, apart from a scattering of new houses, resemble sets from one of those Powell-Pressberger films made during the last war. They are almost completely unspoilt.

As for the Dengie marshes themselves, as I wrote at the beginning of this account, you may think that knowing your county as you do, if you’ve seen one salt-marsh, you’ve seen them all. Well, not quite, actually. The Dengie marshes – much of their 11,000-acre seaboard reclaimed from the sea – feel eerily different to the marshes anywhere else along this coast.

Dengie, which is almost prairie-like in appearance seems vaster and lonelier. For it was here that St Cedd, over a millennium and a half ago came to preach his faith among the resistant East Saxons. All these centuries later, in all seasons, his ancient premises remain open for business and the pilgrims are still beating a path to his door.

The people who worked these ague-ridden marshlands, up until a few decades ago, were tough old fishermen, wildfowlers, horsemen and farmers. They did battle with an ever-encroaching sea for their living and were reportedly, a breed unto themselves.

With land-useage having changed so greatly in recent years, much of those flat and endless marshes are now important nature reserves.

Chastened by this knowledge, and casting aside all thoughts of the Sacred Sandal of St Cedd’s, I really owe it to the place to return here on a warmer day and have a more serious look around.