I immediately shot to the bit about STATS19 and noticed this rather carefully worded quote (page 147):
Car occupants are the road user group with the largest number of casualties, the largest diversion in trends from the in-patient data and the lowest reporting rate. If there were small but systematic changes in reporting or recording of these injuries at the serious/slight margin part of the rapidly reducing trend in English serious casualties might be explained. However, there is insufficient data at present to strongly support this supposition and more work needs to be done.
[my bolding]
They know, you know

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