Nigel,
I did and was asked what evidence I had that the problem was widespread - which is why I'm asking the question because the design fault is clearly apparent even to a year one engineering student but I have no means of knowing if anyone else has suffered the same problem. I get the impression that someone needs to be electrocuted through the back falling off one of these plugs before anyone will take the problem seriously.
I've also complained to the BSI who allowed their kitemark to adorn this plug to suggest that they are wrong to have done so. Their response is the usual 'corporate BS' with the standard comment "BSI prides itself .... etc, etc" and telling me that any discussion they have with the plug manufacturer cannot be reported back to me for "reasons of confidentiality between BSI and their client (the manufacturer)"!
Bryan N
August 2012