"nospam_lonelytraveller_nospam"
wrote

There's a wide sub surface walkway to just in front of kings cross
station from the overbridge at the former station, and its currently
disused. I'm sure they could do something useful with that, even if
its just adding a glossy entrance to the lighthouse building so you
don't need to cross that road junction.

When was it last in use? I imagine that after the Met and Circle lines moved
to their new station there wouldn't have been all that much interchange
to/from Great Northern suburban and Midland trains at Kings Cross Met (aka
KX Thameslink), although some passengers must have continued to change to
the tube lines. But IIRC the tunnel between KX Thameslink and the tube
station didn't open until the BedPan electrics started.

Peter