It has been suggested that really robust specimens like this one are showing 'hybrid vigour'. Since I consider them all to be hybrids, I rather think their environment might just have something to do with it instead.
The next sequence shows the gently graded colour variation from lilac to white:
That last one with no colouration whatsoever and yellow pollinia is known as Dactylorhiza fuchsii, ssp. o'kellyi, and is confined to western Ireland. No comment.
I raced to have a close look at these two when I saw them, and sure enough, the spike is short and the lower lobes are really frilly. A perfect Heath Spotted Orchid?
Not in my book...they just happened to be the only two with their feet submerged in the stream, and were less than a metre away from identically-coloured CSO with dry feet.
Still with orchids in mind, have a look at this shot of the hoverfly Helophilus pendulus:
The hoverfly has some green objects stuck to its antennae. A much closer zoom in shows that they are, in fact, the pollinia of an orchid:
They must be quite irritating to the hoverfly, because it was quite clearly trying to remove them. Maybe hoverflies aren't perfectly built for this pollination task.