Cheerier islets improved part of England (14)

I believe the answer is:

leicestershire

'part of england' is the definition.
(I know that Leicestershire is part of England)

'cheerier islets improved' is the wordplay.
'improved' is an anagram indicator.
'cheerier'+'islets'='cheerierislets'
'cheerierislets' anagrammed gives 'LEICESTERSHIRE'.

(Other definitions for leicestershire that I've seen before include "somewhere in the Midlands" , "Cricket team" , "Source of cheese" , "Melton Mowbray county" , "English county" .)

I've seen this clue in The Daily Express.

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