Elaphe sclaris - Ladder Snake
Snakes are difficult to identify as they slither past. Ideally you have to examine
the eye and head scales close-up!. However from the photo this look a bit like
a young adult Ladder Snake - found only in Iberia and Mediterranean France.
The young usually have a bold "ladder" pattern which is reduced to
two simple stripes in adults. The young eat grasshoppers; Adults eat rats, small
rabbits and nestling birds. Large prey are constricted (squeezed to death)
(Ref: Field Guide to the Reptiles and Amphibians of Britain and Europe, Arnold
and Burton - Collins 1978)
Photo: David Skipper