The Pigs Lucas distributor is still an easily serviceable item with parts widely available. However upon inspection the moveable plate had come loose and fused the contacts. This was preventing the Engine from running, not helped by the advancing weights sticking.
At this point I decided that an electronic ignition conversion was the best option. This kit was supplied by Classic Car Heads and after weeks of chasing them with phone calls etc I received and installed the new ignition kit. This runs with only 12v applied to the ignition coil, prolonging its life. It is also much more reliable with no capacitor required, resulting in stronger sparks from the spark plugs and thus improving the running of the engine. No more setting contact points!