Some of their bumf:

In amongst this riot of form and colour is all to easy to forget the part that native British species can play. Not only are they beautiful, elegant plants that look 'just right' in nearly every garden but also because they are the plants that our native British wildlife is best suited to simply because the flora and fauna of these islands have evolved together ensuring a perfect ecological fit.

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I doubt a butterfly or a bird believes in evolution any more than I do, nor are they likely to prefer a local native to a local alien if it tastes OK and is available, any more than I do when I shop at Tesco's.

None the less, it is nice to have a dash of green in the riots of reds, blues and yellows.

It's suprising how many naturally occuring British plants have green flowers. (Not that I can name one.)

It's not only butterflies that pollinate flowers in the UK, it's flies and beetles too, birds as far as I am aware have nothing to do with polination in the UK, unlike the humming birds in the Americas and other honey feeders.

Native insects are far more likely to pollinate native plants, its all to do with the physiology of the insect and the plants have honey guides that are invisible to the human eye, but clear to the spectrum seen by insects.

Some of the man-made hybrids are poor seed setter because they have been bred for our eyes and not the pollinators, so wiggly wigglers are totally correct.

Pollination biology is a fascinating subject and far more complex than you seem to be giving it credit for.