Don’t be alarmed if you spot one in your compost heap, they are harmless, except to pests like slugs
If it looks like a snake but blinks, it is a slow worm: Anguis fragilis. That is the helpful hint for the squeamish who might worry about the appearance of a greyish brown or black legless lizard in their garden compost heap. Your reaction should be delight, as slow worms are entirely harmless and a gardener’s friend; they eat slow-moving prey like slugs and other garden pests.
They are the most likely of Britain’s reptiles to be found in gardens but like any damp and boggy place on the edge of woodland or in tufty grasslands. They are most numerous in Wales and the West Country but can appear anywhere in Britain although populations can be patchy.