There are some people's accounts of closures on the tube last Thursday here (Evening Standard).

In particular, the southern end of the Northern line:

I was due to pick a work colleague up from Balham at 7:15am, but when I got there I was greeted with Tube emergency vans, police and hoards of people being turned away from a closed station.

All very strange they must have known something was going to happen, they surely had a tip off. As I drove along the road, (which also follows the tubes) they were all shut and hundreds of people were queuing for buses.

when I reached Oval, which was open there were two armed policemen in a road next to the station, which for a quiet area like that is extremely rare.

the northern line was shut from Morden to Stockwell. They blatantly knew something was going down, they just got it wrong and are hoping no one mentions anything.

But this is denied by another person:

At Balham station yesterday morning from around 6.30am I believe. As there was no service between Stockwell and Morden the stations would have been closed to the public for obvious reasons that being NO TRAINS. The LUL vans you saw at Balham would have been the response team of engineers trying to fix the train. There was no cover up on the Northern LIne it happened, I know because I work on the line. There were also delays to rest of the line due to suspension, any police or ambulances would have been sent as standard to assist with any passengers taken ill or having a panic attack if train was in tunnel when it stalled and couldnt move.

However, by 7:15 the line had been shut from the south for a long time, so I don't understand the comment about "police or ambulances" needing to assist.

Also, someone notes that the Picadilly line was not working:

Got to Arnos Grove, 8.30 AM Thursday. Unable to enter station, sign reads "due to fire, Piccadilly Line suspended between Arnos Grove and Kings Cross - 08:00". NB this is well before first bomb at Liverpool St/Aldgate at 8.51AM. FOAF saw fire engine outside Caledonian Road station at 8.25AM. Was this a suspected fire, totally separate from the bombings later on? Or was there some vague intelligence re. an attack on the Tube that morning? Note that other lines (Eg. Northern Line) were also experiencing problems, but is that par for the course on any given day on London's Tube network? Or am I just being overly suspicious about how events were reported, given the 'power surge' headlines? Discuss.

BTW Big up all the emergency rescue workers, medics, police, etc. True professionals - thank you.

But according to today's news (example), the northern end of the Northern Line must also have been closed, this being the reason that the person with a bomb who got on the bus did so:

The youngest of the group, Hasib Hussain, 19 is thought to have planned to head north, but the Northern line was closed so he headed to the street above King's Cross and caught a No 30 double-decker bus. It was nearly an hour later, at 9.47am that he set off his bomb in Tavistock Square, killing at least 13 people.

I should like to see an exact timeline of which lines were closed before the first bomb went off, and for what reasons.