I have been out in the field over the last couple of days and have seen a few mating balls of Grass snakes, plenty of Adders out sunning themselves but the Grass snakes are rather noisy in the bracken.
Here is a lovely sight that I saw this morning, a melanistic Adder basking with 2 Grass snakes and a normal Adder.
Here is some footage of a mating ball from yesterday.
http://www.youtube.com/watch?v=4aLUNtm7HlU
A one eyed Grass snake