A UNIQUE oil painting of a County Durham chapel by an artist with a cult following is to be auctioned.

The painting of the ruined Sockburn Chapel near Darlington was created by one of the Alderson twin sisters, who usually worked on canvases together.

It is dated ’68 and signed by Dorothy Margaret Alderson.

Dorothy and her twin sister Elizabeth Mary, who were born in 1900, were Yorkshire-based painters best known for their horse, dog and countryside pieces.

They were also renowned for their unusual practice of working on the same canvas together at the same time.

The chapel painting is being sold at Anderson & Garland’s Fine Art Sale in Newcastle on June 14 and is being auctioned on behalf of Rosemary Barkes, whose mother grew up at Sockburn.

She said: “The odd thing is that it was only done by one of the Aldersons and we don’t know why.

“I haven’t seen any other pictures by only one of them; they mostly painted horses – one from each end.

“My family lived at Sockburn Hall for about 30 years.

“The chapel there dates back to about 600 and inside in the roofed area, there is an effigy of a Crusader with a little dog at his feet.

“His legs are crossed and his toes are turned in, which means he did two Crusades.

“The Sockburn Worm is said to be buried in a field nearby.”

The ruined Sockburn Chapel is a scheduled ancient monument that dates to before the Norman Conquest.

Nearby is the Grey Stone that marks the spot where Sir John Conyers is said to have slain the Worm of Sockburn, after he had gone into the church in full armour and offered up his only son to the Holy Ghost.

Anderson & Garland is expecting a lot of interest in the painting, because of both the subject matter and the continuing interest in the work of the Alderson sisters.

Auctioneer Fred Wyrley-Birch said: “The chapel is one of the earliest Christian churches in the country and has an interesting history.

“The Alderson sisters still have a very large cult following and a lot of people like their work very much.

“They were known as Dolly and Betty and famously would work both sitting at the easel, with one painting the front end of a horse and the other painting the back end.

“We’re expecting the painting to be hotly contested.”

The lot has an estimated value of £150 to £250.