Great or Little Britain

A follow-up to Great Britain, "lofty adjective" 

According to the Oxford English Dictionary, this "lofty adjective" was first introduced around the 14th-century. It cites the passage by some chronicler (Robert Mannyng), who wrotes "Bretayn þe grete was . . ."

The OED  briefly follows the history of the phrase:

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The fuller name Great Britain has been in use since the Middle English period, originally to distinguish the island from Brittany, which was then also called Britain (see below). Compare also the more Britain (1582 or earlier). Compare post-classical Latin Britannia maior , maior Britannia (12th cent. in a British source), Anglo-Norman Bretannie maiur (mid 12th cent.; also grant Bretaigne). The name gained a political aspect in connection with the union between Scotland and England: in 1604 James I was proclaimed ‘King of Great Britain’, and this name was subsequently adopted as the official name of the new kingdom created in the Act of Union (see quot. 1707). Under the Act of Union of 1800 Great Britain became part of the United Kingdom of Great Britain and Ireland . Since 1927 the country's official name has been United Kingdom of Great Britain and Northern Ireland.
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"Great" Britain was initially a term for the island in distinction to Brittany. A duchy of Brittany was also referred to as "Britain" from early Middle English onwards, a region that later emerges as "Little Britain, Britain the less, the less Britain" as opposed to "Great Britain."

I wonder whether the difference of the terms depended either on the territorial proportion or what Stevens describes as emotional "loftiness" (or both), when such distinction was made.