The company that supplies water to large tracts of the most prosperous and populous parts of southern England has belonged to a German electricity company, RWE, for the past five years. Thames Water's customers are worried about leaks, a long-running drought and water quality, but when it comes to foreign ownership either they do not know about it or they do not care.

That is just as well. RWE wants to sell Thames Water and the list of those said to be considering dipping a toe in is pretty cosmopolitan: the government of Qatar, an Australian bank, a Swiss infrastructure investment fund and a pension scheme for, among others, Ontario's firefighters and school administrators.