This might help with dates. According to this Census Mary MacNamara was born 1865 and had still not married in 1901. This would knock things back a few years.

Patrick Quigley, the tailor, was born 1868.

John Considine, who could possibly be Michael Considine's nephew was born 1876. If the song was sent home to him when he was 6, Mary MacNamara would've been 17 then and the tailor Quigley 14. I reckon that the tailor Quigley mentioned in the song could be this tailor Quigley's father.

The 1901 Census of Clare - Spancelhill - Muckinish.

Considine Kate Hd RC Read-Write 47 Female Farmer Widow Co. Clare
Considine John Son RC Read-Write 25 Male Farmer's Son Not M'd Co. Clare
O'Connell James Brother RC Read-Write 43 Male Not M'd Co. Clare
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MacNamara John Hd RC R&W 45 Male Farmer Not M'd Co. Clare English
MacNamara Mary Sis RC R&W 36 Fem Dom Serv Not M'd Co.Clare Irish-Eng
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Quigley Mary Hd RC Read-Write 60 Female Housekeeper Widow Co. Clare
Quigley Patrick Son RC Read-Write 33 Male Tailor Not Married Co. Clare