So how big was the terror cell? Four more held as balaclava-clad officers raid flats and swoop in the street | Mail Online

So how big was the terror cell? Four more held as balaclava-clad officers raid flats and swoop in the street |

English Law allows authorities to arrest people for conspiracy to commit a crime. It does not matter that they were not involved doing the crime, but merely the fact that they talked/ about/planned it.  Charges may be dismissed later and folk set free.
It looks to me as if they are using this conspiracy law to crash in doors, all over London, on fishing expeditions.