It turned out that it had escaped from a house further down the street of terraced houses and arrived via the cavity,thinking was that it mistook the tails for small snakes and crawled in to join them,quite funny really as there was a bit of a stand off between me and a local chap who we called out as he kept snakes.The creature was still alive when I arrived and after pulling service fuse and finding it alive we sent for him,he assured me it was a corn snake and harmless but didn,t want to touch it as he didn,t like electric,and didnt believe the supply was dead I wasn,t prepared to touch snake as I didnt know what it was, eventually after convincing him the supply was dead he removed snake.It was nearly 3 feet long and lived for several hours afterwards.