On 12 Sep, 00:05, (Colin Rosenstiel) wrote:

An overrun all the way from Drayton Park to Highbury and Islington?
Surely not?

It runs as far as the south end of H&I SB platform.

Having it in the platform means that a train that has entered the
tunnel pan up can be visually inspected, and that the AC-DC changeover
can be cycled through (i.e pan down if still raised, go DC, go AC pan
up onto dead line, go DC.).