G4S are very shifty, had experience with them during the London Olympic Games. They offered jobs to inexperienced people and trained them before hand. Had two friends apply with no previous experience and after a 1 week seminar (answers were very clearly suggested during tests) they were both granted full SIA licences that covered them for the next year. In their class were lots of people who couldn’t even speak the language, dubious ID requirements which weren’t strictly adhered too.
If there’s going to be a company that will be involved with a “we don’t know how a terrorist used our recruitment methods to gain entry to such a VIPlace” it’ll be G4S guaranteed.