I@n wrote:
Picadilly between Hammersmith and Barons Court apparently. Details
sketchy at the moment.

It appears to have been an eastbound Piccadilly near Barons Court (though
the TfL/LU sites refer to a derailment at Hammersmith station). The train
remained upright and there were no injuries. Further details from BBCi News
:
-------
"It is believed the wheels of the rear carriage came off the track at 2125
BST as the train carrying 76 people was travelling between Hammersmith and
Baron's Court stations. A BTP spokesman said there was no suggestion of
crime. He said the passengers were in the process of being transferred to
another train to take them on to Baron's Court.

A Scotland Yard spokeswoman said there were no other trains involved in the
incident, which occurred 200 yards from Barons Court station, she said. The
train is believed to have come off the rails at some points. "There have
been no reports of any injuries", she added.

Firefighters, British Transport Police and Underground staff were being
taken to the scene on another train to help passengers."
-------
"Some points" presumably refers to a connection with the siding between the
e/b and w/b Piccadilly tracks.

Piccadilly line suspended between Acton Town and Hyde Park Corner. District
suspended west of Earl's Court (or possibly South Kensington if you believe
the Tfl/LU sites).

--
Richard J.
(to e-mail me, swap uk and yon in address)