If I remember correctly, unfortunately (and I may very well be completely wrong here but do have a hazy recollection of being told something like this at a meeting with the other Neil) somebody was ill, i.e. Neil himself or a family member around that time (2001).
Also the model of the the PLH business was based, and I imagine possibly very reliant on, the Pre-JAR Instructor Rating system - wannabes worked towards and gain their PPL (H) followed by lots of hour building to the requisite amount for an instructors course, all the time putting money in an account with PLH. I imagine the JARs were perhaps not too conducive to the continued success of PLH. Dunno.
Just my understanding/weak recollections. More than happy to be corrected.