[Gremlin]

Long before the fire, in the days of steam and when the tracks were very busy it was compulsory to walk through the tunnel before you could join the "Big boys gang".
There are plenty of little shelters cut in the wall to stand in while a train passed.
To joing the "Junior boys gang" you had to walk through Winterbutlee tunnel at Walsden which was 503 yards long.

There is book published about the Summit tunnel fire with plenty of facts about construction etc.
The centrefold photograph showing fire belching out of two of the vent shafts was taken from my brother's courtyard on the hill opposite.