I followed Stuart XK's great instructions for doing this on an XK150 coupe. Unfortunately, when I got to the end, removing the light strip and spoiler, all I found was the FM antenna. His pictures clearly show the same part I'm trying to replace, but it's just not there. Not sure if it's because mine is a convertible, or a newer model or something else.
Anyone have further info on this? Thanks.

 

As per manual:

 

PROBLEM RESOLVED

I found a loose wire connector inside the trunk cover; it accepted my new gps antenna. I attached it with velcro to the underside of the cover. GPS signal is fine now.

I don't know how it became this way, but there are no holes under my spoiler to accept mounting of the GPS antenna. Just the FM antenna is mounted in there.

 

The antenna isn't mounted, per se. It is stuck with double-sticky tape.

 

I appreciate your help.

 

And a previous owner would appear to have unstuck it and thrown it away, leaving just the cable behind.

Richard