Paul, you are a star!
I have just 2 issues now! (tell me to go away, honestly I'll understand!)

When I run it, it includes the very top level folder that the document is saved in.
01 comes up as '01 This Folder', I should get '01 Introduction' and I get '01.01 Introduction\' instead. So then everything is then 1 level out.
It also gives me the spurious '\' at the end of that as well. That's only happening AT THE 01.01 folder level. It doesn't do it at other levels?

Finally the hyperlinks don't now work!
I get a 'security concern' pop up which I accept then I get 'an unexpected error has occurred' error. When I hover over the link it shows File:///c:\01 - Introduction - I cant see where the extra c:\ is coming from. Is that linked to the issue of being 1 level too far down the tree?