A London Underground spokesman: "There was a very low speed derailment on a Piccadilly Line train.
"There were no reported injuries. As far as we understand at this time only the last wheels on the last carriage came off.
"We don't know the cause of the derailment. There will be a full investigation."
How this will affect the Piccadilly Line, we'll have to wait and see. The derailment and crash on the Central Line in January caused actual injuries to 32 passengers and then months of havoc on the line itself as large proportions of the line remained closed. The tube paid millions in compensation to passengers whose journeys were totally screwed up.
Apparently part of the track at Piccadilly in that area was badly rusted and then snapped. Good job, as I travel on this part of the line every working day.
In the light of the recent report about passenger overcrowding only issued two days ago (see my blog entry) the London Underground is certainly going to be in the spotlight again.
This is the first accident to happen since the tube was privatised so it's clear there's going to be a major investigation here and rightly so.
For more on the derailment see the various reports from Google News.