Hedge Parsley or sometimes know by the name of Upright Hedge Parsley is a small umbelifer, that might be mistaken for a rather ratty specimen of Cow Parsley.
It does flower rather later than Cow Parsley, usually late June through to August by which time Cow Parsley has finished flowering completely. Also it is a much smaller plant, and a little bit straggling despite being called Upright.
They are quite common in hedgerows and open woodland rides. So they do tolerate some shade but not deep shade, as such I would describe them as more of a hedgerow plant rather than a true woodland plant.
The seed heads are quite distinctive with rough hooked seeds that are more or less circular also often a purple colour.
The leaves are very similar to those of Cow Parsley but are somewhat more hairy, this is a photo of one of the upper leaves near to the flowers, the lower leaves are larger and more parsley like.
I see this plant quite a lot in France, in the Poitou-Charentes area which is a region I visit quite often, and also write another blog about called Poitoucharentesinphotos. Anyway a corespondent said that he thought this plant was showing up in England more this year (2018) than usual and this could be caused by the hot weather. There may be something in this.