Might be Dietes

Doubt Dietes would survive in most of the UK :-) Could be Iris japonica, Japanese wood iris. These produce sprays of white, orchid-like flowers in late spring or early summer, at least in my climate.

I. japonica sounds most likely. Claire Austin (author of "Irises: A Gardener's Enyclopedia") wrote it "is the most commonly cultivated crested iris in Britain" and that she grows it outdoors in Shropshire, England.

I grow a hybrid named 'Nada' and it blooms fairly reliably each winter (indoors). After a fan has bloomed it grows upward on a "stalk" that reminds me of bamboo. My Mother recently broke one off by accident and placed it in a glass of water. It formed roots after a while and is now potted up.

Here are some thumbs of 'Nada'. It's stalks could be called a "spray".

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