Ferry terminals constructed by the defendants in the River Thames caused excessive silting. This disrupted the plaintiff's business by obstructing access to their jetty and they had to spend large sums on dredging operations. Their claim in private nuisance was dismissed because the jetty itself was unaffected and they had no private rights in the property of the river beds. However the HL held that a claim in public nuisance usually entitled a claim for damages and that reliance on statutory authority was only a defence if D exercised their authority with reasonable care (not done) and therefore D was liable to P for the cost of dredging that would have been avoided if the terminals had been designed to avoid siltation as much as possible.
Lord Templeman (majority): One cannot complain of private nuisance if one has no proprietary interest in the thing being damaged i.e. the river. “An individual who suffers damage resulting from a public nuisance is, as a general rule, entitled to maintain an action.” An alternative design was possible which would have limited siltation to 25% of that which actually occurred, so that the costs awarded are the costs of de-siltation had only the “inevitable” siltation actually occurred from a reasonably careful use of statutory authority (i.e. 25% of what actually occurred).