March of Helen? Wrong — of Welshmen (3,2,7)

I believe the answer is:

men of harlech

'welshmen' is the definition.
Both the answer and definition are plural nouns.
Perhaps you can see a link between them that I don't see?

'march of helen? wrong' is the wordplay.
'wrong' indicates anagramming the letters.
'march'+'of'+'helen'='marchofhelen'
'marchofhelen' is an anagram of 'MEN OF HARLECH'.

'of' is the link.

(Another definition for men of harlech that I've seen is " Traditional Welsh song and military march".)

I've seen this clue in The Times.

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