worm from Ecrins NP (1 Viewer)

I realise that species id is almost undoubtedly impossible from the photo, but any idea of what sort of worm this is would be of interest. It was very approximately 50cm long.

It looks like a mermithid nematode e.g. Mermis nigrescens which is a parasite of insects. When they break out of the insect they've been living inside they burrow in the soil, stay there for a year or two and then in showery weather emerge to lay their eggs on vegetation. What time of the year did you see it and what was the weather like?
Horsehair worms are similar but are more water based.