As this thread came back to life, I thought I'd report that the Semforite is now in use and works just like the Cascamite I knew and loved, only whiter.Abranet (Toolstation for common grits) for an abrasive and semforite for an adhesive if you miss cascamite.
https://www.maragon.co.uk/glue.html#Init
I also got some Abranet to try out (on a whim when I came across a one-off deal on a small selection of cut pieces). It's very good as an abrasive but it has a pretty thick, fluffy back for velcro-ing on sanders etc. That's not a problem in itself, but it makes the sanding surface too spongy for my current project. Even glued to a block, it tends to round over the edges of flat surfaces if you apply *any* pressure while sanding them. I need the edges to stay utterly planar with the rest of the surface for this job. I tried clamping hard onto the wood sanding block while gluing, which did make a very solid firm surface and stopped the rounding, but it completely compromised the non-clogging behaviour too. Gummed up in no time. As I said though, it's a good abrasive and it will find other applications - so no loss.
Cheers