I planted a random collection of old unlabeled seeds. Most of what sprouted i recognised but what is this plant? The flower is about an inch across. The leaves and stems are very delicate. It also sprouted in a pale orange colour and a blueish colour
Common name is flowering flax, scientific name: Linum grandiflorum. It's an annual, and not native to the UK (but originates from North Africa). It can be found in British gardens, though, see Gardener's world webpage.