The latest al Qaeda video carrying warnings of more explosions in London will do little to reassure the British capital’s already jittery passengers. Thousands of extra police have been deployed in a bid to calm frayed nerves just over four weeks after suicide bombers left more than 50 people dead.Undercover officers have also been out in force, mingling with commuters to try to spot would-be bombers. Though many people seem to be steering clear of London transport, some using the buses and trains were philosophical about their decision. “You’ve got to put it out of your mind, and continue like normal as best you can. It’s the best way to respond to what’s happened in the last month,” said one passenger. “I am sad for what happened but life goes on. So here we are again,” said another man travelling on the tube. Yesterday the Picadilly underground railway line became fully operational for the first time since the attacks on July the 7th. In a separate development, two sisters charged under anti-terrorism laws are due to be questioned over keeping information from police about the bungled suicide attacks two weeks later.