Your magpie Nick, was almost certainly raised by a human before being released/getting lost into the wild. Since the general consensus is that human raised magpies, crows, etc, lack the survival skills to exist unaided in the wild, it is nice hear of an example to suggest otherwise. I had a completely tame magpie (for 18 years) who was an excellent mimic of not only me, but also car alarms. IME adult wild magpies are impossible to tame properly – hand reared they become incredibly tame.
I’ve also seen a pair of crows high up in the sky constantly harassing a bird of prey as it was flying along (don’t think there was any food involved but corvidae don’t like birds of prey as the provide competition) The bird of prey (don’t know what species) just regularly tilted as it flew to show the crows that it was fully armed, ie, with talons, that made them keep their distance.