“two reds two whites are the only correct way”
IIRC there are some less obvious differences in the PAPI setting and obstacle clearances at LCY, which require the glidepath to be followed accurately.
Due to the steeper approach angle the actual altitude difference between PAPI ‘beams’ will be larger than that for lower angle approaches, i.e. at LCY you are further below the glidepath with 3red 1white – closer to the obstacles, than for a 3 deg approach. In order to maintain a similar relationship with a 3 deg approach, the angle between the PAPI lights at LCY may have been changed; can anyone confirm/refute this.
Also, I recall that the ILS obstacle clearance surface uses the equivalent of a CAT 2 installation to provide clearance over all of the obstacles (some may have been removed now); this required the use of a higher accuracy ILS GS beam (possibly also a ‘tighter’ beam for the same reason as the PAPI above).
There should be a note somewhere about the need to use either an electronic or visual glideslope for all approaches into LCY.
“having a 'pink' can help avoid the situation in the video”
First, a well set up PAPI system has no ‘pink’ zone – only red or white with a sharp transition between the two (beware frosty mornings where ice or lamp warm up may appear pink).
Second, flying below the approved glidepath does not prevent an inadvertent harsh touchdown. In addition, it might invalidate any landing distance credit for the steep approach – check the performance section of the AFM.
“Landing on the right spot … I don't believe you need to do anything else than the right thing.”
Much better than thinking about how you were helping others - from the overrun area whilst they all divert!