WOT, thanks very much for the info, interesting!
A few months back, I had an issue with the laptop which would mean that the CPU speed was limited on low battery.
See this link: CPU speed at 0.48Ghz during low battery - - Windows 10 Forums
The resolution was to disable BDPROCHOT in throttlestop, which was only effectively a workaround. However, after the BIOS update, the issue appeared to resolve itself after sleeping and waking the laptop!
I will see what I can do when I return from my trip.

Many thanks.