A similar question was posed on the Guardian website "Lions have been used in British heraldry since the 1100s. Who in Britain at that time would have seen a lion and how?"
There are some interesting comments. Apparently Lions still lived in north Africa and parts of Europe until the late 19th century.
Lions have been used in British heraldry since the 1100s. Who in Britain at that time would have seen a lion and how? | Notes and Queries | guardian.co.uk