@sarge your quote is from a job ad from a particular school - and that is exactly my point re. CCF SSIs. The terms of their employment/appointment are entirely down to the school; as are their school duties (if they have any) outwith the CCF. Until very recently, there weren't even any standard TORs for SSIs; there certainly aren't any in JSP313.
An SSI does not have to be employed by the school. They can be appointed by the school, approved (in the words of JSP313) by the relevant Army Bde; but do not have to be paid by the school. I know personally of several SSIs in CEP schools who are not employed - ie paid - by the school; they simply claim one of their 51 days VA on their SSI day (although they may have other paid duties in the school outside the CCF).
My point is simply this - whether we are talking about a CFAV "proper" (and whether community CF or CCF) or a CCF SSI - the Chaudri case is established legal precedent (the ruling of an Employment Appeal Tribunal) that where payment is made for "work" - ie duties performed - other than reimbursement for expenses; the individual receiving payment is an employee, not a volunteer.
This is 100% the crux of the matter, and is the underlying reason for the introduction of the CF Commission, Volunteer Agreements, and the re-branding of pay as Volunteer Allowance (which it isn't, legally).
In my view the MOD has moved forward with the CF Commission first because, if it were to come to a court of law, it would be easier for a commissioned CFAV - as a reservist - to establish that they were an employee; and therefore also entitled to the current reservist offer (as a part time employee) under employment law. As a by-product, by taking CF Officers out of the Reserve Forces, it also eliminates Service Complaints.
Logically then, the next step is - as we have discussed - to gradually phase out VA, since it is payment for work, not reimbursement of expenses.