If we continue the said thread here, then, when the forum is fully operational again, this thread can just be added on to it and it will all be seamless. I presume so anyway.
I think you may have made a similar mistake to the one I made with numbers. The deaths you quote are England and Wales whilst the population figure (UK) you give includes Scotland and Ireland.
However the ratio idea still works but with different numbers.
year deaths population Rate/1000 ASMR
2020 608,002 59,829 1016.2 1043.5