|View from the 1st floor of Lion pub|
There is a board next to the structure which usefully tells us: "It is thought to have been built between 1740 and 1770 although the exact date is unknown. The structure is unique and its purpose has been puzzled over. Once thought to be a folly or the remains of the north side of a medieval bridge, the structure is in all probability a cattle screen, built to prevent cattle wandering downstream whilst crossing the ford.
The Farningham screen is the only one in the country to have been constructed in such an ornate way and would probably have been built whilst the Hanger family owned Farningham Manor...."
There's some interesting information here too by a rambler.