Tube evacuations at a glance (BBC News)

Two weeks after the terrorist attacks in London, three Underground stations have been evacuated – Warren Street, Oval and Shepherd’s Bush – with early reports of smoke.

Early indications from the attacks on 7th July were of electrical failures, so unfortunately, given the current climate and feelings in London, even an unknown or apparently unrelated incident (particularly one that warrants evacuation) may be seen at its worse.

The entire Northern Line has been suspended, and Waterloo Tube station is also closed due to a security alert.

Given the state of our transport system, this could be purely a mechanical or electrical failure caused by old and under-invested systems. We all know what else it could be.

Yet again, London watches and waits…

…sirens, if only psychologically, seem more frequent and louder; commuters do their best to carry on; our brave and wonderful emergency service staff prepare themselves – just in case.

Update Thursday 21st July 1.55pm: Dummy explosions using detonators only have sparked the evacuation of three Tube stations and the closure of three lines, a BBC correspondent has said. This isn’t officially confirmed, as far as I can tell

Emergency services also attended an incident on a route 26 bus in Hackney Road in Bethnal Green.

Update Thursday 21st July 2.15pm: One person was injured at Warren Street, although the person’s condition is unknown.

Westminster Underground station evacuated.

Tony Blair and Ken Livingstone cancel meetings.

UK Government’s emergency-response team Cobra meets at Downing Street, with Prime Minister Tony Blair and Foreign Secretary Jack Straw attending.

Update: Thursday 21st July 2.55pm: Met Police chief Sir Ian Blair says this is a “serious incident”.

He appealed to Londoners to stay where they were and said the transport system was effectively being shut down.