Well, I fixed it.
It took me a long time of faffing about going down blind alleys, but what I needed to do was this:
1) Boot from a normal Windows repair disk
2) Open the DOS prompt
3) Run the ‘clean’ command to clean out the MBR and partition table (not clean all, unless you have time to kill – this zeroes the whole disk).
3) Exit the DOS prompt and use the ‘restore system image’ option. I spent a couple of hours trying to find drivers for my USB hard drive (which doesn’t need drivers!) because it was not recognised. Turns out it’s only recognised if you plug it into the BACK of my Lenovo W520, not the side 🙄
Sorted, but now I have to re-PGP my hard drive again.
Turns out that there are not many options for doing system image backups when you are using PGP. So given how easy the Windows system is to use and how the above process is pretty quick, I think I am going to continue to use it and just take the hit of re PGPing my disk if I get a problem.