Do nothing. If you want it to self seed and have more plants then enjoy the fading flower and the seed head. If you do not want any babies then remove the seed pods from the centre of the flower and leave the flower to fade gently over the next few months.

I don't do anything with mine, they flower year after year. Do as Owdboggy suggests.

PS, Millie, I live just outside Maidstone in kent, we could be neighbours.
: ) Gail x

thanks for replies as usual very helpful.
Hi Daff I live in sunny Broadstairs, its a beautiful day here, him outdoors and I are off to Lullingstone Castle today.