Why was England later on called the Great Britain?

The term "Great Britain" was not derived from England. Great Britain is the name of the island that comprises most of England, Scotland and Wales. The name "Great Britain" was first used by the Romans to distinguish the larger island from the smaller one to the west, which they called "Britannia Minor" or "Little Britain". The name "Great Britain" came into common use in the 18th century, after the Kingdom of Great Britain was formed in 1707 by the union of the Kingdom of England and the Kingdom of Scotland.