An unsuspecting building owner is now in possession of a valuable artwork after reclusive street artist Banksy owned up to a new painting that mysteriously appeared on a Welsh wall.

A video posted to Banksy’s official Instagram account on Thursday (Australian time) featured close-ups of the piece that Port Talbot locals discovered on the outside of a commercial garage.

The artwork is believed to offer social commentary on the town’s industrial past and resulting pollution.

With the children’s song Little Snowflake as its soundtrack, Banksy’s video shows images painted on two garage walls that form a right angle.

On one side, a child appears to be playing in the falling snow, sticking his tongue out for snowflakes. The other side reveals the “snow” is actually falling ash and smoke from a fire in a dumpster.

The video then pans up to show the nearby Tata Steel plant, which looms over the Welsh town.

Watch the video below:

 

View this post on Instagram

 

. . . . Season’s greetings . . .

A post shared by Banksy (@banksy) on Dec 19, 2018 at 6:53am PST

“They’ve not dropped a Banksy on us, have they?” a man asks on the video, which is captioned: “Season’s greetings.”

Rachel Honey-Jones, 33, said an artist friend was tipped off about the artwork’s location and stayed overnight to guard it.

“It’s amazing, an incredible addition to Port Talbot,” Ms Honey-Jones said.

The owner of the garage, Ian Lewis, 55, a steelworker for Tata Steel, said he first saw the piece when images spread on Facebook on Tuesday evening (local time).

He said Port Talbot was probably chosen for the Banksy work due to news headlines about the town’s air pollution.

Black dust from the town’s steelworks covered houses, cars and pets in July.

Council workers erected metal fencing around the garage on Wednesday to protect the artwork.

“People have already taken sledgehammers to it and tried to throw paint on it,” Ms Honey-Jones said.

“It will bring visitors and trade and tourism to the county, so it really does need to be protected.”

Banksy, who has never disclosed his true identity, began his career spray-painting buildings in Bristol, England, and has become one of the world’s best-known artists, with pieces fetching huge sums.

His mischievous and often satirical images include two policemen kissing, armed riot police with yellow smiley faces and a chimpanzee with a sign bearing the words, “Laugh now, but one day I’ll be in charge”.

Auction goers were stunned in October when one of his works, Girl With Balloon, self-destructed moments after being sold for £1.04 million ($1.2 million).

The sum paid by an unnamed collector was three times the spray painted artwork’s pre-sale estimate, and equalled a record price for a Banksy. The image was originally stencilled on a wall in east London.

It is accepted the artist himself devised the mechanism that caused it to be shredded.

In Australia, three stencils by Banksy in a Melbourne laneway were  destroyed in 2016 to make way for a new door.

The artworks, painted on a wall in AC/DC Lane, were smashed and the rubble thrown into a skip.

-with AAP