One of Europe’s largest snake species is crawling up walls and into attics in the UK, seeking warmth for breeding, scientists say in a new study.

Aesculapian snakes, which grow up to 7ft long, are not native to the UK. They went locally extinct during the last Ice Age, and were not seen widely in the UK for 300,000 years.

But they have become an invasive species now, researchers say, surviving in warm corners in the UK. They were introduced during the 1970s to Colwyn Bay, North Wales, following an escape from the Welsh Mountain Zoo.