In message , Boltar
writes

On a related theme , does anyone know how far the running tunnels extend south
of aldwych?

Only as far as the station itself (on the corner of the Strand and
Surrey Street) as far as I recall.

Do they reach the river?

No, I don't think there was any concept of an overrun tunnel when the
line was built - it just stopped at (or within a few feet of) the
platform end.

--
Paul Terry