Thanks again John.

I have been in person to enquire at the PRC commissioners office in Wan Chai and the staff there told me to apply for the Z visa and complete the process back at a consulate in the UK. I suppose if one has the documents that say apply in HK issued from within China, they may have luck, but I wouldn't want to risk the nailbiting and "what if?"

I do wish the mods would make this a sticky:

http://www.fmcoprc.gov.hk/eng/fwxx/wgrqz/t1071458.htm