The "F" on the rear facia fell off. Needless to say, the local JLR shop can't put it back on and the "F-Type" trim comes only as a set. I am embarrassed to ask such a small question but what is the best adhesive to put it back on. I was thinking about using double sided tape which should be non-damaging but not very strong, or maybe rubber cement which may be too permanent. Is there some magic stickum ? Thanks.

 

 

Looks like it will do the job just nice!
But a tad pricey for one little letter, a cheaper solution would be a small tube of black (or clear) silicone RTV sealant/adhesive.
I have used it for years for sticking all sorts of badges on all sorts of cars, including the repositioned black painted leaper on the F-Type, and it has never let me down.
Another plus for the RTV is it takes a few minutes to cure/set which means you can wiggle the badge into the exact right position beforehand, and any excess cleans up with turps.
The main downside (and the only one I have ever encountered) is you need to be very careful applying it to the back of the badge, it has to be applied thinly and not too close to the edges otherwise it squishes out past the edges when you press the badge in place.