As the alternator was not happy on the way to Northampton and back it thought it was best to take it off, check all connections and pull the regulator to make sure the brushes were not worn out.
Did that, all looked ok, popped it back together and put it back on the car. Got the tester out and fired the car up and guess what, yep you guessed it, its all working fine now!!
Why is it electrical stuff does that!
Took her for a run this morning to get a coffee and she was running spot on and charging just as she should be. I think I will probably get a new regulator just in case (Bosch 1 197 311 028 regulator) as it will be handy as if it happens again I can swap it out and see if it cures it. I need to see if I can find a different one from the Bosch as they are £45+ which is a bit steep!