It used to be said:

NTSC = Never The Same Colour
PAL = Pictures At Last

But I am genuinely puzzled by this thread. I don't understand how people can think that the difference between DVD and Blu-ray and between standard and HD broadcast is not obvious, even in a PAL set-up. My experience is that the high definition formats are substantially better resolution than the standard formats - it's not a subtle thing. How can anyone have difficulty in discerning between them? I simply fail to understand why there is a question.

BTW, to the comment that screens are smaller in the UK because rooms are smaller, that also means viewing distance should be less. One should offset the other. However, I do think it's possible that the Which testers were simply at too great a viewing distance to see the difference, in which case they were testing their eyes, not the format.

MC200, Twinstore, 808v6/ID41 -> DSP8000SE (+ SB Touch, Sony BDP-3300, SKYHD, legacy cassette player)
2nd system: MC200 analogue out, Linn LP12, SB3 -> Quad 34 -> M60 rosewood
F80 (Rubino Micallizzato)
F80 (Rosso Corsa)