Trouble removing top retaining nut on capri struts !!

Anticlockwise with a rattle gun never fails.

Rattle Gun or not, ALWAYS allow 15 mins minimum for subject NUT to soak in WD40 or RP7 or DWF...........a small piece of cotton wrapped around nut to act a "fluid-store" that's fully soaked helps.
Those lucky enough to have access to a product called REDUCTEUR, will find using REDUCTEUR provides faster and more successful results....... usually found at specialty stores like Enginering Tools Suppliers and Bearing Suppliers.
I thought it was expensive, until I became addicted to it for the HOURS of frustration it has saved me, and avoiding damage to the components, my knuckles and my brain! .........best addition to any toolbox hands down!
Go halves with a mate: you'll both get decades of help from 1 can, as it only gets used when cheaper fluids fail ! 
.............Anti-clockwise to undo !

Not surprised to read that they are buggered (presumably after trying to get them out), as I'm having the same trouble with some Escort ones. Bilstein sell the retaining nut as a separate part for their struts, although maybe not in Australia. Try part number B36-816 A1 (for 51mm 2L Escort struts anyway; no idea what size Capri inserts are).
 
You may find the same basic part number available with a different two letter suffix, e.g. B36-816-B1, as in this case:
https://www.summitracing.com/int/parts/bsn-e4b36816b1. I don't know why, although I suspect it is for different thread pitches, so do your homework before you plonk your money down.
 
I think these are an improvement on the factory nuts, as you can use a $4 C spanner from eBay to get them off. I've no idea why Ford decided to use a nut that you have to wrench from the inside, apart from maybe frustrating the home mechanic!

Yes, I can confirm new nuts always come with new inserts. If they're not included, do not buy them as they should be included as I have found after more than 100 sets I have sold.