There are few certainties in life perhaps, but along with death and taxes it may well be worth adding avoiding shares in Jarvis.

The rail maintenance contractor managed to wipe about £80m off its value after it slashed its profit forecasts by more than 60%.

You don’t have to be an elephant to recall the firm’s debt for equity swap, the end of a process of decline that began with the Potters Bar train crash.

But the latest bad share day looks to have come from a sudden realisation in the board room that the company isn’t working on terribly profitable contracts (thanks to low quality rail work, uncertainty in its plant business and a move by Network Rail to buy its own vans instead of hiring them from Jarvis).

KBC Peel Hunt, Jarvis’ broker, said that the profit warning was “highly disappointing and unexpected”. Small wonder: KBC recently put out a note on Jarvis, saying “we believe the shares have the potential to rise substantially over the next year or so”.