Update: the system doesn't allow me to export a members posts; however, I've reached out to people far more technically capable than myself, and there may be a way to extract John's post using more technical means.
I've sent an appeal for assistance to one of the UBB team and I do hope they can help. If not, I'll be going the 'old school' route of review and then 'cut-copy-paste' each one of Jack the Lad's posts into a document!
Fingers crossed!