My 02 Sahara has that bottom left design and I have seen them on other uk wranglers of the same year the headrest is height adjustable. Maybe check with
@Kiwi TJ to see if this is a right hand drive thing ?
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From what I can see they ran these seats with the split headrests over here from late 2001 (51 plate so basically 2002 model) to 2003. Could be some law that was linked to the headrest on the older seat design being too low. Not sure though as everything I have tried to look up on car seat laws here are linked to child seat regulations