Question: Who wrote the Irish folk song about Irish moonshine or a beverage traditionally distilled in a small pot still?

Context paragraphs:
Dunville's Three Crowns: Dunville's Three Crowns was a rare pure pot still whiskey distilled by Dunville & Co at the Royal Irish Distillery in Belfast.Similar to Dunville's other whiskey Dunville's VR, Three Crowns was distilled longer and used more sherry casks for the maturing process.

Redbreast (whiskey): Redbreast is a brand of single pot still Irish Whiskey produced by Irish Distillers.  It was originally produced by Gilbey's, a Dublin spirits merchants using distillate sourced from Jameson's Bow Street Distillery.  However, in the 1980s, the brand was purchased by Irish Distillers, the producers of Jameson Irish whiskey.  It is the largest selling single pot still Irish whiskey in the world.

Mrs. McGrath: "Mrs. McGrath" (also known as "Mrs. McGraw", "My Son Ted", "My Son John", and "The Sergeant and Mrs. McGrath") is an Irish folk song set during the Peninsular War of the early 19th century.  The song tells the story of a woman whose son enters the British Army and returns seven years later having lost his legs to a cannonball while fighting against Napoleon presumably at the Battle of Fuentes de Oñoro (fought between 3 and 5 May 1811).  The general theme of the song is one of opposition to war.  Along with "Johnny I Hardly Knew Ye", it is one of the most graphic of all Irish folk songs that deal with sickness and injuries caused by warfare.  Irish folk song collector Colm Ó Lochlainn described "Mrs. Grath" as "known to every true born citizen of Dublin".  It was very popular among the Irish Volunteers in the years leading up to the 1916 Rising and has been recorded by many singers and folk groups.

Powers (whiskey): Powers is a brand of Irish whiskey.  Historically a single pot still whiskey, the flagship "Powers Gold Label" brand was reformulated as a blend of triple-distilled pot still and grain whiskeys during the twentieth century.  However, in recent years, several single pot still variants have been relaunched under the Powers label.

Ketel One: Ketel (Dutch for: "Pot still") One is a liquor brand of the Nolet Distillery in Schiedam, the Netherlands.  Ketel One Vodka is distilled from 100% wheat in copper pot stills, filtered over loose charcoal, and rests in tile lined tanks until ready.  Ketel One Vodka is named after the original copper pot still, "Distilleerketel #1."  The alcohol content of this spirit is 40% (80 proof (US), 70 degrees proof (international)).  The Nolet Distillery also makes Ketel One Citroen, Ketel One Oranje, and Ketel 1 Jenever.

The Hills of Connemara: "The Hills of Connemara" is an Irish folk song written by Sean McCarthy about Irish moonshine, or Poitín.  In the song, the drink is referred to as "mountain tea" ("tay" to rhyme with "day").  The punch line to the song is that the tax collectors ("excise men") find the cache of moonshine and begin "drinkin' it straight".  "Tae", pronounced "tay" is gaelic for "tea".

Arrack: Arrack, also spelt arak, is a distilled alcoholic drink typically produced in South Asia and Southeast Asia, made from either the fermented sap of coconut flowers, sugarcane, grain (e.g. red rice) or fruit, depending upon the country of origin.  The clear distillate may be blended, aged in wooden barrels, or repeatedly distilled and filtered depending upon the taste and color objectives of the manufacturer.  Arrack is not to be confused with "arak", an anise-flavored alcoholic beverage traditionally consumed in Eastern Mediterranean and North African countries.

Poitín: Poitín (] ), anglicized as potcheen, poteen or potheen ( ), is a traditional Irish distilled beverage (40%–90% ABV).  Poitín was traditionally distilled in a small pot still and the term is a diminutive of the Irish word "pota", meaning "pot".  The Irish word for a hangover is "póit".

Single malt Scotch: Single malt Scotch is single malt whisky made in Scotland.  To be a single malt scotch the whisky must have been distilled at a single distillery using a pot still distillation process and made from a mash of malted grain.  In Scotland, the only grain allowed to be used in a single malt whisky is barley.  As with any Scotch whisky, a single malt Scotch must be distilled in Scotland and matured in oak casks in Scotland for at least three years and one day.  (Most single malts are matured longer.)

Single pot still whiskey: Single pot still whiskey is a style of Irish whiskey made by a single distillery from a mixed mash of malted and unmalted barley distilled in a pot still.  Somewhat similar to single malt whiskey, the style was defined by its inclusion of unmalted raw barley in the mash in addition to malt.  However, on occasion, small amounts of raw oats or wheat may also have been used.  This unmalted component is said to give single pot whiskey a "spicier bristle" and "thicker texture" than the otherwise similar single malt whiskeys.  If the whiskey is not distilled totally on the site of a single distillery, then it may be termed "pot still whiskey", but not "single pot still whiskey".

Supporting paragraphs: The Hills of Connemara Poitín
Answer: Sean McCarthy