Woodwalton Fen in Cambridgeshire is an ideal habitat for Grass Snakes. Lots of long grass and reeds to hide in, open places to bask in the sun and water filled ditches for hunting. Grass Snakes aren’t poisonous, they are excellent swimmers and their favourite prey are frogs and toads. Immature Grass Snakes would prey on tadpoles and insect larvae. The best time to see them is early morning when they find sunny spots to bask in.
The photo below was taken in Spring 2016, there were five or six snakes entwined together. I also got some video footage of this amazing event.