In message , RPM
writes
The tripcock arm is on the 6 foot side so accessibility is restricted
to the sucidally insane unless a block can be arranged with the
signaller.

To reset the tripcock manually requires more than a little brute
strength. If possible a brick, large chunk of ballast or piece of wood
is needed to perform this function.
On LT 38 and 62 stock this function was carried out by securing the
train, climbing out of the cab central door and pulling a loop of
string, just under the right hand side of the bodywork at the front.
Not a difficult job, but in a dark tube tunnel you needed a torch, and
very precarious when the juice rail was on that side.
--
Clive