I can not say if this is the answer to the on-going question, however, folks who do scrapbooking have a rather extensive line of "Archival Safe" product. This includes adhesives and ink pads. My wife is a rather serious scrapebooker(works well with all the photos I take)and stamping is big part of what she does. If it is safe for fine art fibre based prints I can not say...but I know it is used on a long list of materials including cardstocks and such.
They also sell a number of pens and such all said to be Archival safe. I would think they are telling the truth as this scrapbook stuff is serious and folks spend a lot of money and time on it(you can take my word on that one).
Thanks for this suggestion - hadn't thought about the scapbook people at all! Will be having a look into what is available in the UK - cheers,