Robert wrote:
Evening all,

https://www.bbc.com/news/uk-england-london-53150748

It will be interesting to see what happened here.

"Passengers narrowly avoided a collision when a train travelled the
wrong way on a London Underground track.

The Chiltern Railways service stopped a few metres in front of a Tube
train at Chalfont and Latimer station in Buckinghamshire.

An image from the scene shows the two just metres apart on the
Metropolitan line on Sunday night.

No casualties were reported and the Rail Accident Investigation Branch
(RAIB) is investigating.

The train caused damaged to points and parts of the track, according to
BBC London Transport and Environment Correspondent Tom Edwards."

There's already a thread on uk.t.l. There's speculation on whether it was
a points or signalling fault or a SPaD.

Whatever it was, it led to the Chesham branch being closed for a couple of
days.