The only way to end this terrorism is for Scotland Yard to infilitrate the British mosques, and DETECT, DETAIN, and DEPORT (or IMPRISON) any terrorist sympathesizer (and I suspect there are many.)
Searching people on the street and chasing them through subways is a stop-gap answer to a problem that will only be solved by aggressively prosecuting for TREASON. As many have pointed out, Britain tolerates many extremist Muslim organizations that are outlawed in Pakistan.
Problem is the infiltrators have to be at least somewhat Muslim, and how can you trust them?