Millsn:
Can't imagine why a two year old alternator that's been used about twice might fail.
Its because Lucas reconditioned alternators are made of cheese. Sometimes you get a good one, other times they are simply a waste of time.
I gave up about 4 years ago and fitted a Denso off a 1988 Daihatsu Charade GTTi, cost me a tenner. Made a bracket and found a suitable belt at Halfords. Charge voltage is around 14.3 volts whereas even a good Lucas can only manage 13.7 volts.
IMPORTANT WARNING Do not buy a Denso alternator off E-Bay etc, they are cheap Chinese copies. Mate bought one from a well know seller when he saw mine,cost him £250 for the kit. 50 miles and 3 alternators later the seller was blaming him for fitting it incorrectly. He got his money back and bought a Denso for £15 from a breaker and its still working fine almost 4 years on. He spoke to Denso and they told him an easy way to spot the fakes, they are labelled as "Nippon Denso" a name Denso stopped using in the 90's when they started selling more parts for European cars.