Perhaps most well-known for destroying thousands of her more famous sister’s letters, Cassandra Austen’s act of what some called literary vandalism overshadowed her accomplished skills as an artist.

But now the artwork of Jane Austen’s older sister – played by Keeley Hawes in the recent BBC drama Miss Austen – are to go on display together for the first time in the house where the siblings lived.

Cassandra was a talented watercolourist, and her best-known piece is an 1810 sketch of Jane that hangs in the National Gallery.

Ten of her lesser-known family portraits and copy work – imitations of other works – have been brought together for an exhibition at Jane Austen’s House in Chawton, Hampshire, as part of celebrations of the 250th anniversary of the author’s birth.

Paintings on display include Cassandra’s watercolour portraits of her niece Fanny Catherine Knight and of her brother James Austen.

Six of the works have never been seen in public before, and four were only recently discovered in the possession of Austen family descendants.

Sophie Reynolds, the head of collections, interpretation and engagement at the museum, said: “This is a small display but a truly exciting one. Cassandra was an accomplished artist and for the Austen family her artworks were as important as Jane’s writing.

“Her skill was akin to Jane’s own, neat and careful, with delicacy and lightness of touch, so to see them is a pleasure in itself, but more than that, for those interested in Jane Austen, Cassandra’s artworks also remind us of the many paintings and drawings in Jane’s novels.”

After Jane died, Cassandra destroyed many of her sister’s letters, an act heavily criticised by later generations of critics angered at being denied insight into the cherished author’s mind.

However, many now assert that Cassandra acted to protect her sister’s memory and reputation, as well as her wider family from hearing themselves mocked or criticised. About 160 of Jane’s letters survived Cassandra’s purge out of as many as 3,000.

The art display has been curated by Janine Barchas, a professor of English at the University of Texas at Austin in the US, whose recent research has focused on Cassandra’s artwork.

“Not since Cassandra’s creative years in this very cottage have so many of her surviving artworks been gathered together in one place,” she said.

The Art of Cassandra opens on 29 April and is free with entry to the house.