[Doctor_Fegg]

> It turns out rail signals were controlled by buried cables without adequate insulation, so when it was wet they literally stopped working

More than that: buried cables without adequate insulation and nobody knew where they were buried.

Railtrack (the unlamented privatised company that originally took on the railway infrastructure) threw out the engineering diagrams. So when the time came to dig up the Great Western Main Line out of London for electrification, signalling failures were a routine occurrence because someone had put an excavator through a signalling cable... again.