a few have noted that the overall vaccine uptake at the national level will be based on the fairly recently released ONS mid 2020 based population estimates. Which are not hugely different from the 2019 based ones, aside a lot of 75-79 year olds being found in England at least.
As NIMS is used for pretty much everything apart from the overall nation calculations; here's a quick comparison at English region level between NIMS and ONS 2020 for each age band and overall.
By band it therefore shows:
NIMS population figure
ONS 2020 population figure
Absolute gap (NIMS minus ONS)
Percentage gap
As London stands out like a sore thumb, a borough breakdown at overall population and by the younger age bands will also follow.