Thames Water’s owners only have themselves to blame for the write-downs | Nils Pratley

It looks as if USS simply overpaid and underestimated the effort and catch-up investment required

We continue to view Thames Water as a long-term investment," said the Universities Superannuation Scheme (USS), the 75bn pension fund for UK academics, as it wrote down the value of its stake in the Thames' parent by nearly two-thirds, or almost 600m. Top marks for cheerfulness, but it's a line that recalls the old joke about the definition of a long-term investment: a short-term investment gone wrong.

USS and Canadian pension fund Omers, the other late arrival on Thames' register in 2017 (they replaced the departing Macquarie and its co-travellers), surely cannot have imagined that the long term would stretch quite so far over the horizon. As USS says, it's taken no dividends so far, and the current business plan imagines no income for shareholders until 2030 at the earliest. That's a near-eternity in investment terms for utility assets, which are supposedly prized for their ability to generate steady cash.