Well you need Alba if you want white flowers.

Yes, that's right . . . I just wasn't sure whether there was more than one variety!

Hi, there is more than 1 variety that will give you white flowers, but it depends on what height you're looking for, Campanula carpatica, Bressingham White, for example, has pure white flowers, suffused, blue-green at the bases, but only grows to about 6" high, C persicifolia Alba Coronata, syn 'Alba Plena has semi double flowers, grows to 18", 'Boule de Neige, double flowers, 24", and several more are available, Derek

Many thanks both. I shall look out for the last two you mention Derek.

Campanula trachelium is a British native, and there's a white form of that too

Thanks Andrew . . . well, they say you learn something every day. When I looked that up, I saw that its common name is Nettle-leaved Bellflower . . . and I have MASSES of that in the garden! It is pretty - lilac in colour - and very invasive. Obvs happy in my soil, but I wonder if the white form will also invade?