Before setting off from the navigable source of the River Thames at Lechlade, Gloucestershire to my home in Leigh-on-Sea, Essex where the great river issues into the North Sea, I took the family on a recce. We wanted to find out just how near to the source we could sail a dinghy from.

After trudging across a meadow to a six foot diameter circle of limestone – all that was in evidence of the fresh water spring where the Thames rises – back in June, we then drove to Cricklade. Here the river is a brook and I stripped off to find out how deep it was. Once my son Richard, 7, noticed a tree swing hanging from a willow bough, he, too, stripped off and jumped in. Then his 15-year-old sister, Emily, hitched up her skirt, kicked off her shoes and clambered in to take the above snap – she is a budding photo-journalist.

My wife took some film of all of us splashing about in the cool river water and all seemed perfectly natural. But I do hope the man who was throwing a stick for his dog that day, with his own young children, and who did a double take when he saw my wife with a cam-corder taking film of a naked old man and two half naked children frolicking in the reed hidden waters, reads this. And I hope you, dear reader, will read our account of the river trip in the latest issue of Yachting Monthly.