Well it's the cause of death really. I am not saying the UK government is under or over reporting the raw figures for deaths (all causes) but I think they are being a bit dodgy with their figures on cause of death and especially with the modelling figures they use/used in their briefings.
I think it is very disingenuous to say X countries figures are misleading but the UK is perfect, all governments have an agenda and are not beyond lying to the populous.
A simple of example of this for the UK is that we are constantly given the 127k deaths figure saying they died "in the past year", this is indeed true (near enough a year anyway) but without the context that it covers two winter respiratory seasons. This 127k figure is then compared against a yearly mortality of approx 600k, but again, that 600k isn't spread out evenly over a year so if you took a year that had two winter respiratory virus seasons added together it would be much higher than 600k. So while the figures they tell us are more or less correct, they are being massaged and used in a way that is misleading in order to generate maximum fear and impact.