During the course of my research for ‘Exposed: The National Wiring Scandal Putting Lives at Risk’, I spoke to electricians and industry experts who described how some contractors carrying out safety inspections are incorrectly passing unsafe properties and mis-selling unnecessary upgrades. I also heard about so-called ‘drive-by inspections’, where contractors fill out paperwork without entering the properties at all, undercutting legitimate businesses.

Many readers wrote in to say they had experienced similarly poor practices.

Mal Ronan, a retired principal electrical inspector for the Health and Safety Executive, told us he had come across “a surprisingly high proportion of unacceptably poor inspection and test reports”.

In most cases these were either incorrectly completed or incomplete, but he recalled one case where the test results were fraudulent. “Incompetence, a too hurried approach to the work, and perhaps even some false sense of unaccountability...