Safety changes leave owners of river barges fearing dry times ahead

Operators of historic vessels could be sunk by requirements costing up to 250,000 per boat

Once, thousands of sailing barges plied the Thames estuary. Today, the sight of Will, the largest such vessel still travelling on the waters in London - now converted for pleasure cruises - turns heads.

Passengers on the deck of a giant cruise ship sailing up to Tower Bridge peer and wave at the historic barge below. But Will's co-owner, Mark Tower, 60, warns that such sights - "absolutely part of the Thames maritime heritage" - could soon be lost.