For a few days this week a goat will be king of a small town in Ireland's rural south-west.

Billed as one of Ireland's oldest festivals, the Puck Fair sees locals in the town of Killorglin pluck a wild mountain goat from its habitat and crown him "King Puck" for the duration of the event.

This year's king was paraded through the town on Thursday, where he was crowned by the Queen of Puck — an honour bestowed on a local schoolgirl.

This year, 12-year-old Caitlin Horgan took the crown.

The Queen of Puck crowns a wild goat King Puck at the Puck Fair in Killorglin. ( Reuters: Clodagh Kilcoyne )

The goat appeared relaxed, if occasionally bemused, during his coronation.

"I've seen it for the last 11 years, so it's nothing new but when I first moved here from England I thought it was strange," festival-goer Ben Henry said.

"I heard a fella today saying he's been coming to Puck for 57 years, so that says a lot."

The wild goat was caught from a mountain in Kerry for the fair. ( Reuters: Clodagh Kilcoyne )

The festival will feature music, street performers and a horse fair.

The origins of the event are unclear, though there are many local theories — from a harvest festival to tales of a lone goat fleeing Oliver Cromwell's troops into the village.

Organisers say historical references to the festival date back to the early 17th century.

The first day of the fair includes not only the King Puck coronation, but also a horse market. ( Reuters: Clodagh Kilcoyne )

As for King Puck, organisers say he is to be treated royally during his three-day reign with a diet of ash tree branches, water and cabbage to sustain him until he returns to his mountain home following his dethronement ceremony.

Organisers expect to welcome more than 100,000 visitors during the festival, which runs until August 12.

The wild goat is paraded through the town before being crowned King Puck. ( Reuters: Clodagh Kilcoyne )

Reuters