the point about long grass (actually a misnomer as it is more of a controlled grass length policy) is that it discourages certain species but not all. It has to be part of an overall habitat management regime and it needs to be backed up by active measures such as the BCU. Had the species which are discouraged by long grass been present I would have agreed that the policy was not working
I'm not disagreeing with the result of a long grass policy, but the upshot in the case you quote was that, overall, birds were not being discouraged from the airfield, thus the strategy wasn't working. I can't really criticise the CAA for finding fault when there were birds on the airfield not being scared away.
