Up to 5,000 people work underground at night
London Underground says that up to 5,000 people are at work under London's streets every night to work on maintaining the tube network. These essential works mean that the tube cannot run 24 hours a day.
More top news
Union concern after first Crossrail worker dies
Crossrail bosses have halted all tunnelling involving sprayed concrete following the death of a construction worker.
Network Rail treated bereaved families 'appallingly'
A report on level crossing safety has said Network Rail admitted its behaviour towards bereaved families "has been appalling".
Undercover police probe after Lawrence corruption report
Almost 21 years after Stephen Lawrence was stabbed to death, the Home Secretary has ordered a public inquiry into undercover policing .