I'm familiar with that Table, but I'm not sure that it really helps to clarify things very much. For everything other than 'flexible cables', the tabulations in Appendix 4 explicitly give CCCs for thermoplastic cables at 70°C and for thermosetting cables at 90°C, consistent with Table 52.1. In the case of 'flexible cables' not only is their no such explicit indication of the conductor temp, but there is this rather mysterious reference in the footnotes to these apparent "60°C, 90°C, 110°C and 150°C flexible cables" (with, incidentally, no mention of 70°C or 90°C, per Table 52.1!).
I'm not sure how good a thermal insulator PVC is, but I do rather doubt that it would be acceptable for the conductors to run at 70C (which is what Table 52.1 seems to imply), since the outside could then easily be 'too hot to touch'.
Kind Regards, John