Security Tightened at London Transport Hubs

Al-Qaeda: The True Story of Radical Islam
Jan 7, 2011 — Security has been tightened on railroads, and at airports and other transportation hubs in and around London. It is being reported that officials are saying there is no imminent threat, however there are indications that al-Qaeda or another group could be planning something.
The BBC reports it has seen a letter sent from the Department for Transport to aviation officials that says al-Qaeda "may be considering an attack against a UK airport or aviation sector target" and it describes the reports as "credible".

Source: Planet Data