We thought we'd cracked it at Seven Springs, but Hedley had other ideas. Join us as we chase springs, culverts, and cold feet across the Cotswolds in search of the true source of the River Thames.

The trip from Greenwich to Westminster on the sightseeing river boat takes nearly an hour, a good 15 minutes longer than a similar journey on the nippier Uber Boat by Thames Clipper. But passengers ...