IIRC the Canal Tunnels are to the north of the station box with points
being inserted just to the north of the new platforms to provide
connections to the ECML.

As the south end of the station is on a sharp curve then short of
going under the British Library I don't see how you can fit in a four,
12 car platform, station (bays or islands).

Does the CTRL Act cover what was being built?

OC