Had the belt, water pump and tensioners changed last year but noticed recently cyclic screeching / dry bearing sound on cold morning starts on lower OS front of the engine bay i.e alternator location. Battery voltage when cold on the '763' hidden screen is 11.6v engine off (which seems low) but jumps to 14.5 when started but when I load the electrical system with all the heaters etc it drops to 13.2 volts. I know these things have a habit of letting go suddenly and don't mind getting a new one in as a preventative job but then again don't want to do something that's not needed. Mileage is now 132k and likley it's the original unit. 2012 TDV8 Vogue (L322)

The numbers seem ok on the alternator side- if it was my car- I’d be looking at getting a new battery as 11.6v is too low- should be around 12.6v at least. As for the screeching- I’d be checking the belts are on correctly and check it’s not getting wet or something silly 2009 (2010 MY) 5.0 Supercharged Autobiography
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Thanks. I've been ready to replace the battery for a while but it just keeps going..... Also starting to see a few spurious error codes which are another sign of low voltage. Will check the belts in more detail tomorrow when it's dry. 2012 TDV8 Vogue (L322)

I'd be tempted to change the battery first.
Nov 2020 I needed a "big" battery for an old JCB but rather than buy a new battery for it I bought a new AGM for my RR and relegated the RR battery to JCB use.
At the time the RR had just started to have a few squeals and groans on start up on cold mornings, that's now completely fixed.
Rightly or wrongly my belief is that the battery on the RR was 5 years old and still working perfectly (still is on the JCB) but was possibly starting to lose some capacity so on a cold start the alternator was suffering a very high load demand hence the belt noises but now with a new battery fitted the full capacity means no excessive load on start up.
Could be complete but it worked and made sense to me.

Interesting point - new battery time!
This seems too cheap not to ( cheaper than a tank of diesel.....)
https://www.tayna.co.uk/car-batteries/exide/ek950/ 2012 TDV8 Vogue (L322)