My young sons' school has an (almost) surrounded quadrangle garden, a simple
lawned area with 3 or 4 mature buddlejas, a neglected pond, and some other
herbaceous beds.

I'm told that it's a pleasant area, but "the bushes don't encourage
butterflies". I know it's a subjective opinion, but might it be true? Are
there situations where the buddleja doesn't attract butterflies? Or is it
the local geography, perhaps?

regards, mbb