It's incorrect at a minimum. Reading the source provided:
>76,869 British nationals were recorded in the prison population at the end of the first quarter of 2024. The remainder of the population was made up of 10,422 foreign nationals, making up 11.9% of the total population, with an additional 578 having no nationality recorded.
It seems the 37% figure may have come from an entry in the table breaking down those non-British nationalities by country:
It's isolated and out of context, at the very least it needs an indication of the proportion of foreign born people in London, a major city with a large international population.
At one extreme, if the population of London happened to be almost entirely foreign born then it would seem that UK citizens are working overtime at London crime.
More incorrect than relevant - I suspect you parsed the wrong line.
I'm seeing:
At the end of the first quarter of 2024, there were 87,869 prisoners in England and Wales.
and:
76,869 British nationals were recorded in the prison population at the end of the first quarter of 2024. The remainder of the population was made up of 10,422 foreign nationals, making up 11.9% of the total population
The math checks out: 10,422 / 87,869 x 100 = 11.86%
Why is this statistic relevant?