Technically speaking, she was a member of the union. That is to say she was a member of PAT's subsidiary, PAtT - Professionals Allied to Teaching. But we balked at describing Hill as belonging to the Professionals Allied to Teaching section of the Professional Association of Teachers.
At least she did not add to our column inches by being a member of PAT's other offshoot - PANN (the Professional Association of Nursery Nurses).
Having sundered her links now, it would be accurate to describe Hill as "off PAtT".