Just to throw my pennies worth in:
Competent person (Electricity at Work Regulations)
The following is the definition from the Electricity at Work Regulations regarding a competent person:
"No person shall be engaged in any work activity where technical knowledge or experience is necessary to prevent danger or, where appropriate, injury, unless he possesses such knowledge or experience, or is under such degree of supervision as may be appropriate having regard to the nature of the work."
The statement from the EAWR is very broad and is often the most confusing aspect of the whole electrical industry. As of yet, there is no legal structure behind being competent in terms of qualifications and experience. It is fair to say though, a relevant qualification would be a distinct advantage in a court of law.
Basically, be it on your own head if you have to try and prove competance in a court of law when someone has been injured/killed after you have carried out a PIR without holding 2391.