Perhaps more importantly, I probably should have added this about the converse ........ it was effectively explaining why even a '2-pole tester' could be misleading if (as effectively is the case with a neon screwdriver etc.) it were used to measure the potential difference between a conductor of interest and earth - since, again, that would not detect a 'broken neutral connection'.
... that this also illustrates that when using a '2-pole tester' for 'testing for dead' it is essential to test (from L and N) to earth (and ideally a 'known good earth', not just a convenient nearby CPC), and not just between L and N, since otherwise one might miss a 'live L' in the presence of a broken neutral.
We should perhaps makes sure that people understand this when we advocate use of a '2-pole tester' for 'testing for dead', since probably the most obvious (and maybe only) thing they might otherwise do would be just test between L and N.
Kind Regards, John