@Quarantino the data from @CoffeeandCroissant is what I was talking about. It gives hospital occupancy by 100,000 k population in that age group, so the data has been normalised by age. So, for example, the rates for the last week data was available were 244/100,000 for the over 85s and 28 per 100,000 in those aged 45-64. To get the absolute number of people in hospital though, which is what matters in terms of relieving pressure on hospitals - I think you have to multiply by the size of the population of each.
Using data from here (www.statista.com/statistics/281174/uk-population-by-age/) there are very roughly 1.6 million over 85s and 17 million 45-64 year olds, so just over 10 times as many. Combined with the hospitalisation data, that means you actually have slightly more 45-64s in hospital than you do 85 pluses. I've done a quick google and can't find data to check but that does seem about right based on news stories I've seen.
@MRex I suspect you are right about the heat maps, so any population bulges by age in any area will make cases look high for that age.