“The Wissey rises in a moated fish pond at a farm in Shipdham near East Dereham in Norfolk and quite soon runs through the never-never land of an army truing ground, forbidden to most of us for over fifty years, left undisturbed for months on end and, crucially, unformed. Thus insulated from modern agricultural pollution, the Wissey is one of the purest lowland streams in East Anglia.”

The walk from St Peter’s church in Ickburgh to the sandy banks of the Wissey is longer than anticipated. On my previous trip here, fortified by a swim in the Little Ouse at Santon Downham, I’d failed to bring a decent map, Tim and I wandering aimlessly through the Brecks in search of Roger’s river ‘that sounds like a whisper’.

This time, I’ve committed the same unpardonable mistake, albeit having worked out how to get to the hallowed banks when scanning an OS Map a few weeks back. So, leading a troupe of six other swimmers, I stride along the isolated country lane, hope turning to desperation.

We hear the Wissey before we see it. I’d thought an inaccessible stream was the main waterway, only for Yanny to walk on a further twenty yards and discover the most perfect swimming spot: A gently shelving sandy beach, with rope swings on the far bank and water tumbling over a retaining wall from under a road bridge.

As well as my usual swimming cohorts Yanny, Tim and Molly, I’m joined today by Suz, Megan and Byron. Each of us ditches our bags and towels away from the inevitable spread of litter along the river’s edge, preparing to take the plunge.

Molly is first in, way ahead of the rest of us as we awkwardly clamber into our swimmers. Tim follows, hollering as always as the water edges ever closer to his waist. Megan and Suz follow tentatively as Byron heads off to explore the nearby woods, led by a cloud of butterflies.

I take my first strides in. The gravelly sand beneath my feet gives way to sharp stones. Flint dots the riverbed, Yanny pointing out particularly sharp bits as I wade towards the white water under the bridge. I peer through and into the ‘never-never land’ of the MOD firing range on the other side. This forbidden land couldn’t look more tempting: Rushing weeds, damselflies darting across the surface and fast flowing shallows all crying out to be explored by non-military feet.

Instead, I content myself with taking to the icy waters on this stretch of the Wissey. The clear river is surprisingly chilly for this time of year. Molly and I reckon it’s every bit as cold as the sea at Covehithe back in April. It’s certainly a lot nippier than the Lark, just a few miles west near Ely and the positively balmy depths of Hampstead Mixed Ponds.

Each of us potters around and swims in our own private reverie. As I tread back towards the bank and my camera, Tim hauls himself up the far bank and grabs hold of one of the rope swings. He makes me a messy splash as he sinks under the surface, standing arms spread as he wades back towards me. This is communal swimming at its best.

The Wissey is unquestionably beautiful, but further downstream it appears clogged, cut grass from farm fields floating along as it rushes towards its confluence with the Ouse. The aforementioned litter is also a disappointing blight and one which I’m seeing at virtually every river spot I swim in this summer. Roger would doubtless have encountered something similar, but it’s still an issue that needs addressing. Picking up a few cans and taking them with you after a jaunt in the country is hardly a struggle.

We gather together on the bank, changing into dry clothes and sufficiently braced as the clouds roll in. It’s warmer out on the road, away from the green tunnel shade of the Wissey. Having come so close a few weeks back, it’s great to have finally taken dip in this most pure of rivers.