wrote:
Given T5 was only opened relatively recently I'm wondering what genius
decided that NOT making the train floor and platform heights the same was
a good idea? The platform isn't curved AFAIR so I don't understand why they
didn't do it.

I'm guessing it must lack the platform hump that allows the T4 platform to
claim to be accessible. But, like you, I was surprised that even modern
Tube platforms don't have level access for the full platform length.

I was there yesterday and couldn't help but notice the contrast with the
excellent alignment of the train floors and platforms on the HEx and HCon
trains and platforms. There's no difference in floor level and almost no
gap. Obviously it helps that the platforms are straight, as are the
Heathrow Tube platforms.

I wonder if the grand plan with the Picc platforms is to introduce lower
floor trains (NTfL) that will provide a long term solution, rather than
temporarily raising some platforms? Short humps provide a temporary
solution in the meantime. This has been the method adopted with the SSR,
where the lower-floored S stock solves the problem, though as you keep
pointing out, it also means you get gaps with curved platforms, such as at
Finchley Road (where a lot of people dash across the platform to catch a
connecting train).