im not going to repeat myself, as Im sure others are as bored of this as I am, all I can say is, I telephoned and spoke with an nppl licence expert, number available via the BMAA, I specifically asked this question, and was given the already stated answer, she did mention, that, people are unclear as to which further exams are needed, and assured me, that ONLY principals of flight need to be retaken, not the already taken microlight version
This all assumes your a current nppl m licence holder, going on for nppl-sep