This is a hybrid of Common Spotted-orchid and Southern Marsh-orchid

This is a difficult genus that readily hybridises, leading to many intermediate forms; the species also exhibit a wide range of variation. Other Dactylorhiza in VC55 are Heath-spotted Orchid, Southern Marsh Orchid, Early Marsh Orchid and Common Spotted Orchid; other hybrids within Dactylorhiza are possible where both parents grow together.

Intermediate between Common Spotted and Southern Marsh Orchids; often very large and long flowerheads, due to the phenomenon of 'hybrid vigour'. 

Stace (4th edition) recommend that 'Identification of hybrids involves careful examination of the characters of the putative parents on site', and evidence of this should be provided; it may not be possibly to identify the hybrid from a photograph unless records are accompanied by details of parent species.

Where the parent plants occur.

Perennial

Widespread in the southern half of Britain.

In the current checklist for VC55 (Jeeves 2011) it is listed as Native; grassland; there are several records.