What kind of orchid is this?

If you were in the U.S., I'd say it's either Platanthera grandiflora (Greater Purple Fringed Orchid) or P. psycodes (Lesser Purple Fringed Orchid).

I don't know where this was growing, or its native habitat, but your photo looks similar to the North American natives named. If seen in the wild in the UK, I'd check for native orchids online.

Whatever it is, it's lovely.

Virginia

UK, I think it's Dactylorhiza.

After looking through the photos here, I think you're probably correct:
http://www.orchidsofbritainand...

Many Dactylorhiza listed here in our database with photos for comparison:

https://garden.org/plants/sear...