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It's a long time since I had an XJ40 but I recall the "sixlight" is an assembly with the bright trim bonded to it and the relevant section in JEPC appears to confirm this. There's nothing I could find to add to this in the Haynes Manual or the full Workshop Manual but other members will have more up-to-date information.
Here's my XJ40 in your part of the World - Cumbria beside Lake Coniston.