I realise that these markers aren't specific but wouldn't most advanced cancers cause elevated Sedimentation rate and C-reactive protein?

No. Nice to be able to help once again, Matt. The sed rate and especially the C-reactive protein result from the liver pumping out extra large amounts of a couple of particular proteins that are stimulated by very particular things that are often produced in inflammation and seldom in pure neoplasia. Forget most (not all) of what you've read about "immune response to cancer" as myth. Best wishes.