Not sure how it works in the UK, but certainly here there are very detailed processes to follow in state schools for recruitment. DH handles a lot of that at his school - a recent application he did there only about 2 people (out of 15) got through to interviews because no-one else addressed all the selection criteria so they are automatically removed! And every position is considered brand new so they can't consider previous applications.

Any chance you are able to contact the person that handled your May application and find out why you weren't successful that time?