Where queen would be executed — or hang, if theory is wrong (12)

I believe the answer is:

fotheringhay

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'where queen would be executed' is the definition.
The definition suggests a singular noun which matches the answer.

'hang if theory is wrong' is the wordplay.
'is wrong' indicates anagramming the letters.
'hang'+'if'+'theory'='hangiftheory'
'hangiftheory' with letters rearranged gives 'FOTHERINGHAY'.

'or' is the link.

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(Another definition for fotheringhay that I've seen is " Castle where Mary Queen of Scots was executed".)

I've seen this clue in The Times.

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