as an update to the above, posted under my previous moniker, at the end of martin zeros video this sunday evening just gone, he clarifies that what he thought was the tib outfall was not right. I tended to think that was just a sewer overflow, and it is sad that the tib does not seem to flow nowadays, wonder if the bricked in arch was the original outfall, since shrunk into a pipe and the final bit of plastic pipe? either way, an interesting watch!!!!