Four previously unseen illustrations by Beatrix Potter have been discovered tucked away in some books in a National Trust property in Suffolk.

Facebook Twitter Pinterest An illustration of a doorway in Melford Hall. Illustration: Beatrix Potter/National Trust

The delicate drawings depict scenes inside and outside Melford Hall, a Tudor mansion owned by relatives of Potter, whom she visited often between 1899 and 1938. Potter and her cousin Ethel Leech were very close, growing up together in Kensington. After Leech married Reverend Sir William Hyde Parker in 1890, Potter would stay with her at Melford Hall.

Her visits were eagerly anticipated by the Hyde Parkers’ three children, William, Stephanie and Harry: William, Ethel’s eldest son, is recorded as saying: “We just loved it when she arrived, for she always brought a cage with mice, another with a hamster or a porcupine.” Potter drew Stephanie and dedicated Jeremy Fisher to her: “For Stephanie, from cousin B.”

Two of the four unseen drawings were discovered by Josephine Waters, house manager at Melford Hall, during conservation work. “I was moving a bookcase together with a colleague, and whilst we were going through some of the books we discovered a drawing tucked inside, it was classic Potter style and we immediately knew it was one of hers,” said Waters. When they showed the drawings to Richard Hyde Parker, the 12th baronet who lives in Melford Hall, he revealed that a third illustration had been found previously, but never attributed to Potter.

“I am never going to forget it, it was the most amazing moment. It made me catch my breath, a real spine-tingling moment,” Waters told the Guardian. “Still now, when I think about it, I get that special feeling. It is the sort of thing you dream of when you are working with a historic collection, that you will discover something new.”

Facebook Twitter Pinterest A fireplace in Melford Hall. Illustration: Beatrix Potter/National Trust

A fourth drawing, of a fireplace, was discovered just weeks ago by Hyde Parker’s wife, Jean. They have allowed the National Trust to display the artworks to the public, during an exhibition celebrating Potter’s connection to the property, beginning 13 July and running until October.

Facebook Twitter Pinterest An illustration of the roof on Melford Hall’s north wing. Illustration: Beatrix Potter/National Trust

While one of the drawings – of the “chamber room”, complete with four-poster bed and luggage – is marked as unfinished, and the exact dates of two of the drawings is not yet known, Waters said: “They give us a glimpse into the world of Beatrix beyond the children’s stories and help us to imagine more about who she was as a person, and particularly who she was when she was on holiday and drawing for her own entertainment.”

Melford Hall is home to a number of Potter artefacts: the toy Jemima Puddle-Duck, given to the Hyde Parker children and thought to have inspired the beloved children’s story, is on display. Several signatures and doodles by Potter can also be found in the house’s visitor books.

The discovery of the four unseen images comes after it was announced in January that an unpublished story by Potter, The Tale of Kitty-in-Boots, will be released in September 2016, with new illustrations by Quentin Blake. The tale, of “a well-behaved prime black Kitty cat, who leads rather a double life” according to Potter, was found in the V&A archives in London in 2014. The museum, which holds the largest collection of Potter material in the world, is also holding an exhibition of Potter’s images, letters and sketches beginning in July and running until October.

The announcement of the discoveries comes just ahead of the author’s 150th birthday, which falls on 28 July.