I'm guessing another snap? If so is it a standard snap that one could pickup at the hardware store? Second how is it anchored? There appears to be nothing behind the hole anymore.

 

No, I believe that is a "fir tree" type fastener for the trim piece. Item #12: https://www.jaguarclassicparts.com/u...onvertible-2-2

 

What year ? up to '93/4 its a screw with a cup washer. Later cars had the coloured fir tree. If it has a small screw size hole the its the screw, if a plastic cup or a big hole then its a plastic fixing cup and firtree.
Looks to me like mine and its the screw.

Some leave the screw out incase the window fails up.

 

I leave it out on my car for exactly that reason. I’d the window motor fails (and they are known to fail) in the up position, in order to fix it you will need to break the glass or destroy the panel.

 

On my car it always fails down. Mainly the right one and I have to remove the trim and tap the motor with a hammer on a regular basis.....