Thanks for your responses on this both. I'm aware that the NR can longer form part of the PPL course as such (as the NQ could), but the steer my ATO is getting from CAA Standards is as stated in my first post, namely 'because a rating is an extension of the privileges of a licence, training for a NR cannot be started until a licence is held'. Whether this is an interpretation and/or assumption of basic licensing laws I don't know, but your replies and those from other sources I've referred to confirm there is currently nothing in the Regulation to prevent training starting before licence issue.
Watch this space!
HW