I think the moral is, do the job right in the first place. Strip all the wiring out as your removing the alternator and don't try to put it all back together in the engine bay. Do it proper on a bench, then feed the cables back as your refitting.
Snotts, going to strip it all down again tmoro. Took it to an auto electrician/ alternator repairer, did a basic check, battery ok, alternator/ wiring unsure but he didn't have time to strip it down without me leaving it outside his place. It's in Grimethorpe which maybe ok if you play in the band but that's about it - its not posh Barnsley
Only thing I can think of off the top of my head is that the regulator can't sense the voltage on the battery properly, so is overdoing it a bit. Outside chance...
These are the connectors to the alternator and the regulator. They are both facing the same way. Look at the wire colours
Has it been rewired, then? Surprised it ever worked. Assuming that they are the wrong way round, easy enough to swap over - poke something small and flat up the connector to release the little locking tangs. You might get away with no damage to the alt...we’ll see ...