Thanks everyone, so a courtesy update:
1. GEOFF289 - certainly an important thing to check, but no switches left on - I tend to be fairly stringent with switches after too many flat batteries and the resultant shits from getting either jump starts or replacements.
2. So, have replaced the alternator, a new voltage regulator and a new starter solenoid just so it's not a time-consuming piecemeal drama. The old wiring has certainly seen better days, so probably due for a full overhaul replacement loom i.e to do away with all the shoddy shit people have done to her over the decades e.g. upgraded stereos, speakers and bodgie workarounds.
3. Good new: she's ALIVE! It starts and runs well ... pessimistically, at least for the time-being. Don't know if she'll hold a charge because of some other parasitic drain - so will disconnect the battery and leave her on a trickle charger.
Now she's decided to spring a power-steering leak of some significance - it's been leaking for a while, and it's time to have that addressed ASAP.
Anyone know the best way to address the power-steering leak please? It's the original unit, so is a rebuild a choice and any suggestions in the Western Sydney area?
Again, appreciated and thank you in advance.