Originally Posted by OAP Pete

From ex Auto sparks...now retired, you are correct the Warning light must come on when turning Ignition on, go off on starting, then giving 13.8V / 14V at battery, your readings engine running suggest Alternator U/S, BUT do check at the battery the "Fuseible link" [ thin type link ] these were fitted back in the day, over the years "Rot away", give heavy Volt drop and eventualy Alternator failure, most were done away with, if you don't see it on your car its been removed, and the heavy Red Alternator cable is now direct to the battery, which is perfectly OK. Peter.