I notice that the NICEIC have recently updated their note about the major changes between the 16th and 17th editions:
Rumours regarding changes to regulation 522.6.6 of the public draft edition appear to be confirmed - to quote:
"The requirements relating to cables concealed in a wall or partition have been altered so that protection by a 30mA RCD is an additional requirement for ?unprotected? cables (e.g. twin and earth cables installed in a chase less than 50mm deep); it must be emphasised that such cables must still be installed in ?safe? zones."