I believe they were actually invented but Avon, in conjuction with Atlantic College. I think they first found a market in the military, but I am not sure.
Tony Lee elliot writes an article on the Hot ribs website and you might be able to contact him through that and he also used to manufacture Ribs under the Flatacraft Name (bloody good they were too)
Also Halmatic have been making them for a long time so they may have some info, likewise the press office of the RNLI
www.hotribs.com
www.avoninflatables.com I think