According to Georgia's Glossary[]
A long leather strap that you attach to a collar and put around animals' necks. Then you can take them for "walkies" without them running under cars or attacking other animals. However, the exception is Angus. Even before he ate his lead it was more a case of him taking me for walkies, or rather me being dragged around behind him up and down hills and under cars as he searched for things to destroy (i.e., poodles).