Thanks for the replies. Some interesting behaviour during some testing. With the additional 2 settings turned off (speedstep and speedshift) the cores are essentially parked at 1.7ghz P cores, 1.2ghz E Cores, over my short period of testing:
Max CPU Package Power: 6W
Avg CPU Package Power: 1.612
It is also possible with WiFi and Bluetooth switched off to achieve total system power draw as measured by draw from the battery to -2.5W = 20.83 hrs of battery.
My average with the laptop in this state just typing out this comment and during general usage with this laptop was -5.5W (Wifi + Bluetooth now on) = 10 hrs of usage.
Core clocks seem very low, but the machine is not noticeably slow in anyway for general usage. Probably not the best solution for everyone, but it does significantly improve the battery life.
Interestingly, in this state in a multi-core performance test, with the CPU using between 13-15W maximum the Cinebench R23 Multi score is 5798, which is faster than an i7-1165G7 with no power limits @ 4904.
