Saw this growing and took a few pix I reckon it is a wild onion flower. I had one growing there a few years ago but they cut it off with the strimmer. If they cultivated this to a gladiola size flower gardeners would grow them and boast about the colours etc. My Nigella damascene plants from last years dropped seeds have come on fairly well after that very late spring.
Another few days should see the flowers open I hope.