Terrorist cells.

What they have copied is a system developed in the seventies by the western intelligance agencies. The need to know. There were so many spies in the Cia, NSA, FBI, GCHQ, MI5, Mi6 etc. who were informing to the Russians that they formed small cells outwhither nobody knew about.
However here is the problem - inside the smallest cell something may want to betray the inner secrets. Hence FUC8888 al and his boys have a problem but so do the Met and all of the agencies listed above - Al and his boys work for them. Remember James Bond/Joyce.
Gordon Insider