"MIG" wrote

Maybe terminating trains at Stratford means that there is no room for
anything from Hackney?

London Overground (NLL) trains via Hackney Central are still running into
Stratford Low Level - those platforms are useless for trains from the GEML,
and it sounds as though Lea Valley trains are terminating at Tottenham
Hale - in any event they have their own platforms at Stratford which can't
be used by anything else.

Peter