I think LGW has more manual pinch points than LHR, which is largely automated. I can't recall many reports of correctly labelled tags going to the wrong place from there, the usual problem being some printer issue meaning a bag - or even dozens of bags, going to the destination of the previous passenger(s)..... So always glance at the airport code before the bag goes down the hatch, not that it would have helped here.

LGW and LCY have the additional issue that if the bag had gone to somewhere with a less than daily service, instead of somewhere else on a twice week rotation, the bag could spend a week getting to its final destination.

All baggage is scanned to a particular level of security, if it is OK for Malta, it is OK for Verona, Edinburgh or New York.