Surprisingly, Sid hints harbour is in old country (7,8)

I believe the answer is:

british honduras

I'm a little stuck... Click here to teach me more about this clue!

'old country' is the definition.
'British Honduras' can be an answer for 'country' (British Honduras is an example). I am not certain of the 'old' bit.

'surprisingly sid hints harbour' is the wordplay.
'surprisingly' is an anagram indicator (a surprising ordering of the letters).
'sid'+'hints'+'harbour'='sidhintsharbour'
'sidhintsharbour' with letters rearranged gives 'BRITISH HONDURAS'.

'is in' is the link.

Can you help me to learn more?

I've seen this clue in The Telegraph.

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