Ilford made a POP paper of their own until quite recently. Could this be manufactured again ? The current staff may not realise that, Simon Galley et al weren't working for Ilford when I visited Mobberley few times in the early 80's. In fact the research & sales departments didn't know that the "Barfen" liquid emulsion at that time was made by Ilford. It was only when someone from Ilford sales approached the company behind Barfen branded products that they found it was from the Ilford Nuclear emulsions division, based in London.
So Simon could the Ilford POP paper be manufactured again. Last time I saw a reference it was in a Ilford kit for schools as an intro to photography, making photograms etc.