Interesting observations from Spandex and Fatflyer - whenever I have flown the approach myself I have always started a 3 degree descent at the MAP (D5 CGS at 2000') and (as Fatflyer points out) this means we make the D3 CGS turn with 2R2W on the PAPI at about 1400', and then continue on 3 degree down to the threshold.
But indeed as Spandex alludes, on looking at the card more carefully, I suppose that there is nothing to stop you descending to below 1400' before the turn, then making a level turn and intercepting the glide slope from underneath, which is what the BA flight did. It doesn't seem the smoothest or most stable option though, and quite a strange way to interpret the card.
