"We started at Thames head at the start of today's morning, and we haven't found the Thames yet!" he told the French news agency AFP as he walked along the bone-dry riverbed.

Ed Pratt began his journey in Gloucestershire - where the river originates. Its starting point, known as Thames Head, does not have a fixed location, but arises from a group of shifting springs.

Asked where the "new" source of the Thames is, Mr Naulls said: "You are moving quite a distance down the river to find signs of an actual river – I stood in the Thames that was wet and river ...

Rising at Thames Head in Gloucestershire, the Thames flows into the North Sea via the Thames Estuary. On its way, the river drains the whole of Greater London.

It is 58 million years old and 346km long. It has 80 islands, 45 locks and more than 200 rowing clubs. It is crossed by 104 bridges and is home to 100 species of fish; briefly, in January 2006 ...