One of the many facts I (and all my school friends) picked up at an early age was that of the three main UK snakes, only the adder had a poisonous bite, and could be easily identified by its unique markings. The grass snake and the slow worm are harmless.
It seems this sort of homespun education no longer applies (replaced presumably by how the various game Apps behave).
https://uk.yahoo.com/news/rylan-clark-left-terrified-snake-083339789.html
Were you cognisant of the grass snake's harmlessness, or would you too panic like rylan?