That talks about what to do at the interface of old & new colours.Albeit only 'informative' 2.1(i) of Appendix 7 appears to indicate that red is still acceptable for 'identification' (which, as we know, can be achieved by oversleeving) of line in an 'old' (I presume 'old colours') cable.
Table 51 specifies brown, irrespective of what colour is being oversleeved.