Investigators have concluded that the bombs that ripped through three subway trains and a bus on Thursday were relatively crude devices containing less than 10 pounds of explosives each. That finding supports a theory gaining momentum among the authorities that the plot was carried out by a sleeper cell of homegrown extremists rather than highly trained terrorists exported to Britain.

This might help explain why no one had heard of the group that claimed responsibility and why they made errors quoting the Koran in their message. Let’s hope hate crimes against innocent Arabs and Muslims don’t soar in Britain now.