This squat, unassuming little building has an explosive history. People used to see it up on a rocky crag overlooking the Irish Sea.

For many, its purpose was a mystery so one woman posted some photos on Facebook and asked for information about it. Now its role may have become clearer.

On a page called Residents of Old Colwyn Past and Present, Donna Smith posted these photos of the building. She asked if anyone knew what it was used for apart from latterly a toilet.

There were a couple of theories. A number of people suggested it was a seafront lookout while others said it was a storage building for explosives at the nearby quarry.

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One reader confirmed that the hut was used as a gunpowder magazine. He said explosives made in a Gwynedd factory were stored there then used to blast the walls of a quarry.

He posted: "Gunpowder was delivered from Cookes Explosives Factory at Penrhyndeudraeth. It was packed in cardboard boxes and stored in this what we caĺled the Gunpowder Magazine.

"Also there were small tins of detonators which were used for blasting and also rolls of fuses and boxes of fuse lighters. There was only one key holder, the quarry blaster.

What was this building in Old Colwyn used for?
What was this building in Old Colwyn used for?

"He had to remove hob nailed boots to enter and wear 'magazine slippers'. Hob nailed boots were deemed a danger to cause 'sparks'. Harry Foulkes was the 'blaster'.

"He often stood outside with doors wide open puffing away at his Woodbine. He also had another concrete building where he would cut fuses to length."

The reader said the building in the photo was once surrounded by a wall. "There was a stone wall surrounding it. An exterior metal door with treble locks and internal wooden door, The interior was lined with pitch pine boards, floor, walls and ceiling to keep it dry."

He added: "Blasting (in the quarry) was twice daily 10 a.m. and 4 p.m. By 1963 the quarry had become too near to the railway tunnel that goes through Penmaenhead and for safety reasons had to be closed."

Granite quarrying in Penmaenmawr goes back at least 5,000 years. Commercial operations began in Penmaen in 1830 and rock is still being extracted from Penmaenmawr Mountain.