4 separate stages: lab skills test, techical test, personal interview and tour of site. The order however is different for each candidate and the technical test requires a very specific knowledge of the biochemistry of specific pesticides (not hinted at in the job description at all) and the guided tour provides answers for this test so if you have this tour before the test, you will pass.
They don't recruit by merit in other words. And they are very unpleasant and rude in the test and so I would not want to work for them now,