Was given a frozen vacuumed packed leg of lamb that is four years old it safe to eat?

No, it is not safe to eat a four-year-old frozen vacuumed packed leg of lamb. The lamb may have been properly frozen and packaged, but the quality and safety of the meat will have deteriorated over time. The leg of lamb could have potentially developed harmful bacteria or other microorganisms that could cause foodborne illness. It is important to follow safe food handling and consumption guidelines, including cooking meat to the proper internal temperature to ensure its safety.