So would YOU go up and start working on a junction box without testing for dead, just on the assumption that someone else had isolated the circuit?
No, I thought not.
We seem to like to "blame" somebody, but to me, it looks like the person to blame, was the person standing on top of the ladder who had not personally isolated the circuit, and had not personally "tested for dead" before starting work.
The "storage boxes" probably broke his fall and saved him from worse injury.
I'll get criticised for this last statement, but even a simple neon screwdriver or volt stick would have showed him it was live and he would have come back down the ladder and gone to make it safe properly.
Anybody that just takes someone elses word for it that it's dead, and grabs hold of the terminals, is just an idiot.
I do feel slightly sorry for the contractor firm, who appear to have been found guilty of having an incompetent employee not trained to undertake electrical work safely.
And this has nothing to do with Part P. It's all about the guy on the top of the ladder was not competent to do the job he was doing, but someone else got the blame, not him. Tightening the Part P system would do NOTHING to solve that sort of problem.
headbang 
