Thank you for your very kind words Rhiannon.

I've just checked the river Wylye out as I hadn't heard of it before, what a very pretty little river and you are completely correct it has no connection to the Thames.

I guess I was thinking northwards of the river Kennet which (according to Wikipedia) has the rivers Og, Dun, Lambourn, Enbourne and Foundry Brook running into it. Six miles to the west of, and through Reading, it also supports a secondary channel known as Holy Brook which formerly powered the water mills of Reading Abbey. The Kennet meets up with the Thames at the Kennet Mouth just outside Reading.

So the Winterbourne and Swallowhead Springs are connected to the mighty Thames - this gives me a little thrill as I spent much of my adult life living in London and walks along the Embankment often left me wondering about its its mysterious source (which I know is actually near Cricklade).

Best wishes
june