yes...but!!
Thanks to both Eck and FF for comments. The Standards Doc is the CAA take on the matter, but I am interested to find out what lies behind that. As it happens I like flying/teaching NDB holds, but the point in case is where the published procedure involves a hold on the LLZ is it really necessary to repeat the hold elsewhere.
As it happens we are in the process of agreeing non-published holds at IAF on RNAV approaches, but not for test purposes.
If anybody could point me towards relevant ICAO docs it would be great.