These are snake’s head fritillaries, sometimes called chequered lily, chess flower and leper lily (because its shape resembled the bell once carried by lepers).  Near our former home is one of the most spectacular fields that I have seen with acres of fritillaries in April. The North Meadow in Cricklade near the infant River Thames has been made into a nature reserve because it has 80% of Britain’s wild fritillaries as well as other flowers. They are seldom seen in the wild as they prefer damp meadows most of which have now been drained although there are large groups near the Thames in Oxford and isolated groups elsewhere.   Many have been planted in gardens with these growing in Princes Street Gardens in Edinburgh