It's pretty obvious from reading everything that is on the forum (and from podcast) and has been stated repeatedly.
A car with pre 15/1/2021 BMS, when fully charged, a healthy balanced battery pack is at/near 455Volts.
A car with 15/1/2021 BMS, when fully charged, a healthy balanced battery pack is at/near 450Volts.
"After a full charge my battery shows 439v and a displayed 169 miles of range in 'N'. I had comfort 2 carried out in December but I think I need the latest (15-01-2021) BMS update to get to 450v."
@Dr Dave 's car fully charged (and balanced) now only shows 439V.
He hasn't had the 15/1 BMS installed as his car was at dealer in December.
The range is kind of irrelevant in determining/identifying if it has the bad BMS.
His battery cells are way out of balance, hence it will only charge to a total of 439V out of normal 455V.
The dealer must have installed the dodgy October BMS when it was in.
I can't remember the exact figure that people have found, but after having the 15/1 fix applied, it takes something like 10 hours of balancing to recover each 1 volt.
This would mean after having the fix applied, it's going to take something like 110 hours of balancing to get his battery back to full health.
The longer it is left and the car used/battery cycled, the worse/lower the voltage will end up and the longer it will take to get it back to full health.