Yes, it does, and I am sorry that my answer on this point was incomplete.
I was influenced to state that the vacancy should be filled by election, because the question said that the volunteer had emerged "since the election".
You are quite right to point out, as I should have done, that the governing body may appoint a parent as a governor, when there is an insufficient number of candidates for election.
If the governing body cannot find a parent of a pupil at the school, it can appoint any parent with a child of compulsory school age.
There is no time limit specified for this and I took the view that, if the elapse of time was considerable, the governing body should run an election to fill the vacancy, because other potential candidates might have emerged.