Someone who overheard this conversation emailed me and I thought you might be interested in hearing it.
Anyway, apparently sometime in March, this visitor and a friend had been to one of G4S’ migrant holding centres. They left the visiting room after the visiting hours were finished, and went to the
toilet. G4S forgot about them, switched off the lights and left the visiting building, locking these two people in.
These two people went to what it is the reception before going inside the
visiting area, and they used the G4s's phone to try to reach staff. They managed to speak to staff on the phone at the
reception visitor centre and about ten minutes later they were released from their temporary imprisonment.
Evidently the G4S staff were nice and very apologetic. Still, the visitor is puzzled as to what kind of
security company G4S is when they do not do check out that all visitors
have left the building safely.