The leaves of this plant are the distinguishing feature from V. praecox which has an almost identical flower. They are deeply lobed so that they look like fingers where V. praecox leaves just have serrated edges. The photo I have is obscured by the vegetation nearby and you can't make out the details so this one, taken from cultivation, will have to do instead.

There are a few old records dotted from various places in England but now this plant can only be found in a few places in Breckland and has been reported as reducing in numbers recently (2009).