Paul Scott quotes the RAIB web site:

"At approx 17:35 hrs a northbound Northern Line train was incorrectly
signalled into the High Barnet platform at Camden Town when it was scheduled
to go to Edgware. To minimise passenger delay the following High Barnet
train was signalled into the Edgware platform, and arrangements were made to
exchange passengers and crews between the two trains. When the train in the
High Barnet platform was ready to depart it set off in a southerly direction
for a short distance; the driver saw the lights of the next northbound
train, which was standing at a signal, and stopped the train."

On the Toronto subway system, it happens fairly regularly that the crew on
one train will swap places with the crew on a train going the other way.
I assume this is done in order that a crew without enough time remaining
on-shift to work a full return trip can do a partial one and still finish
at the right place. The TTC uses two-person crews, the guard riding two
cars from the rear of each train and becoming the driver when the train
reverses. So the swap-over is fairly fast if the trains reach the station
at the same time *and* it's one where the layout allows the crew members to
easily reach the opposite platform; otherwise it can take several minutes.

Is it also a common practice in London for drivers to swap between trains
for this reason? If so, it is easy to see how a mental lapse could cause
this near-accident: a driver who changes en route to the train on the
"opposite" platform is usually going to proceed the other way, but in this
specific case it was the same way, not the other way.

I remember another case in London of a near-accident due to an incorrect
reversal. As I recall, this was on the Piccadilly Line at King's Cross
St. Pancras, maybe around 1990. A driver was told to unload his passengers
and reverse on the crossover, but he thought that he'd already passed the
crossover before entering the station. So instead of pulling forward with
the empty train to clear the points and then reversing, he reversed in the
station. The signalling system did not prevent this unusual error, but
the driver of the following train saw him coming and pinched the Drico
wires to cut off the power and prevent a crash.
--
Mark Brader, Toronto | "To err is human, but to error requires a computer."
| -- Harry Lethall

My text in this article is in the public domain.