David of Broadway wrote:

Gates
down the middle of the island platforms at Stratford between NR and the
Central Line - err I think not.

Why not? That's exactly what you'll find at Newark Penn Station, where
the track that carries PATH trains (which operate on a fully gated system)
is in between tracks that carry NJ Transit trains (which don't have
gates). And it's a /very/ busy transfer point.

How wide are the islands though? Leaving aside the shops on those platforms,
the available space for moving down them is so narrow that most of the time
passengers need both sides to move down, especially if you're trying to get
round a buggy. And how exactly would you construct a TfL users only sealed
route from the eastbound Central Line to the DLR platform?