A terrorist doesn't let strangers in her flat because they might be undercover police or intelligence agents, but her children bring their mates home and they run all over the place. The terrorist doesn't know that a kid has bugged every room in her house, cloned the hard drive on her PC, and copied all the numbers in her phone book. The kid works for CHERUB.
CHERUB is not James Bond. There are no master criminals or high-tech gadgets. CHERUB kids live in the real world.
They slip under adult radar and get information that sends criminals and terrorists to jail. For official purposes, these children do not exist