Pink flower in a South Downs wheat field - Bishopstone - 18.9.2015

I have not been able to identify this lovely little flower. It was in a small cluster - I can't remember whether it was a group of plants or one straggly one. It grew to about 12 - 15". The stems are slightly hairy. The leaves seem to grow out where the stems fork and have five oval 'blades'. The buds are also slightly hairy and make me think of the geranium family. Any thoughts on its identity would be very welcome. It will probably be blindingly obvious when someone does name it!