Another question: the BA gold line just told me I can't split my GUF2 into 2 x GUF1s, whereas the wiki/faq says that I can. Is this a case of HUCA or is the wiki/faq out-of-date?

Also, fyi I updated the wiki/faq as follows:
* Under Q: Can I use the Gold Upgrade voucher with an Amex 2-4-1 voucher? I added "as long as both are yours, which means you must travel"
* Under Q: Does there have to be Avios availability in the upgraded cabin to use the Gold Upgrade voucher? I added "but you will need to call BA to make use of this availability"

and the bit I've hit as a problem with the gold line is "GUF2 can be divided to two GUF1 meaning that if you want to use it as a solo traveller, ask first through customer service to divide it." so I may update that once there is a consensus on if one may need to HUCA or if it's just no longer possible.