I learned that one can activate a 'poste restante' facility, but all the paperwork is held by Royal Mail Headquarters, and I have no idea at the moment if they will send paperwork out ot non UK addresses. I think there is a webform on the Royal Mail site www.royalmail.com; the response time varies from a couple of hours to, er , well, still waiting actually.
A lot of dealers won't send stuff to the non-card registered address, especially when the card originator is from outside the UK. Mathers seem to be human beings, where others may simply be robots. Kind regards from sunny Brighton Peter