I think I've identified the species which I saw growing in great numbers [see last entry] on the Pegsdon Hills. Actually this solitary specimen is one I photographed there last year but it's a better close up for the purposes of this entry.

 I wasn't sure what I was looking at. I was reminded of Meadowsweet (Filipendula ulmaria) but that is a taller plant of damp and marshy places not dry, chalky hillsides. So my mind began to scroll through other white flowered wildflowers that might fit the bill. 

 Then the penny dropped. I was on the right lines to begin with. This is surely Dropwort (Filipendula vulgaris) which resembles a mini Meadowsweet and grows on calcereous grassland.