A painting bought for less than $100 (£75) in a US charity shop in the 1960s has sold for almost £190,000 at auction.

Art teacher Helene Plotkin bought the work by Scottish Colourist FCB Cadell in White Plans, New York in 1966, unaware of its true value.

The painting, Interior: The Lady in Black, hung in her living room for 60 years - but the artist's signature was illegible and was only recently identified.

It sold for £189,200, including buyer's premium, in Edinburgh as part of Lyon & Turnbull's Scottish painting and sculpture auction.

The background to the painting only became clear when Helene's son Barry began his own research into it and took it for a valuation last year.

The signature in the upper right of the picture was deciphered using AI and specialists at the auction house Lyon & Turnbull were able to confirm the artist as Francis Campbell Boileau Cadell.

FCB Cadell is one of the four artists known as the Scottish Colourists, who was active early in the 20th Century.

He is renowned for his stylish portrayals of Edinburgh New Town interiors and his vibrant, simplified still lifes.

Helene, who is now 88 and lives in Florida, said the painting stood out when she first spotted it.

"My background in art history and studio practice drew me to this piece instantly," she said.

"The painting had an undeniable, regal presence, but it was the colour theory at play that held my attention.

"The way the pastels were integrated into the composition was both interesting and bold – it was clearly the work of a significant hand with a deep understanding of light and form."

Barry said the family were amazed to find out who the artist was having grown up with picture on the wall.

He said: "We were, as you can imagine, delighted and astounded when we found out the identity of the artist and of the model.

"For mum, it was confirmation of her artistic eye and ability to recognise great talent."