A Dorset museum has acquired an original, previously uncatalogued Augustus John painting at a country auction - which may be worth tens of thousands of pounds.

The rare find was made by Borough of Poole (BOP) Museum Service manager Michael Spender, who is an expert on 19th and 20th century art and the author of numerous books on the subject.

Mr Spender has been searching for Augustus John paintings for Poole Museum, so was intrigued when he came across a painting described as "in the style of Augustus John" in an auction catalogue following a house clearance of a property in the Cotswolds.

Until now Poole Museum, despite close connections with the renowned artist, has not owned any original Augustus John works.

The museum launched its first Augustus John exhibition, which runs until September 30, earlier this year, but works on display have been loaned from other museums from across the country.

This latest work, which turned out to be an original piece painted by the artist around the time he moved to Poole with his family, was purchased for £1,850 using museum donations. However, following positive authentication by Rebecca John - Augustus John's granddaughter - experts think it may be worth tens of thousands of pounds.

Entitled Edwin on the Beach, the painting depicts a young boy, believed to be the artist's son, standing in sand in front of blue water.

The setting, art historians think, may be the Blue Pool, near Wareham.

It is now hanging in Poole Museum alongside 60 other pieces by the artist.

David Boyd Hancock, co-curator of Poole's Augustus John exhibition said: "It is very exciting that the museum has been able to acquire a previously unknown work by Augustus John.

"Appropriately, it comes from one of the most artistically exciting periods in the artist's life, and is of one of his best known and best loved subjects - his own children."

Augustus John (1878-1961) was a Welsh-born artist who was renowned for his portraits.

He spent much of his later life living in Poole, taking inspiration from the Dorset scenery and coastline.

BOP cabinet portfolio holder for culture, Cllr John Challinor, said: "This is an incredible discovery by Michael and I am thankful for the time and dedication he puts in to the museum to ensure that we have the best that Poole’s colourful history has to offer on display.

"I encourage anyone and everyone to take a visit to our wonderful museum and explore the amazing array of Augustus John’s artwork on display and, if you can, please donate so that we can continue to make more amazing discoveries for the people of Poole to enjoy for generations to come."