What makes a sausage "British" rather than just pork in a casing?

A British sausage is defined not simply by pork content but by its seasoning, texture, and method of preparation. British sausages are typically savoury rather than sweet, often include rusk or breadcrumbs to create a softer texture, and are seasoned according to long-established regional traditions. The balance of meat, fat, and seasoning is designed to integrate with a composed breakfast plate rather than dominate it, which distinguishes British sausages from many international varieties.