I used this write up yesterday and it was very helpful, thanks!
Couple of things to note:
1) The document suggested ECP part number 859220020 - currently £27.49. This is a non-stocked part, so i bought 859220021 instead - currently £25.49 (before discounts).
2) The note about the retaining springs is spot on. There seems to be no way to insert the retaining spring in the new struts, so I also opted for the paperclip method, though this was not without difficulty.
After I fitted the first one, I closed the boot to test it, and the seals burst the very first time!

. Oil and gas bubbling out.
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. Luckily I had not wasted much time trying to fit the retaining springs - my test was without these.
So, off it came and replaced with the second strut. This turned out to be fine, so I then embarked on the fiddly job of fitting the retaining springs and cursing a lot. Then I gave up and began fitting paperclips instead (whilst still needing the occasional curse!).
So, one side has been replaced, and there is now sufficient lift to hold up the boot. So, I'll get a refund on the faulty one, and enjoy the thought that the job cost half the price!:bannana: