Beatrix Potter's books are popular in Japan and the USA

Jack Swanston had brought the 23 drawings and watercolours to be valued when the programme visited his area, Dumfries in Scotland.

But he never realised the value of the collection which belonged to his wife's family, which is now going into a bank for safe keeping.

Potter would write out her stories in an exercise book, paste in a few watercolours and a number of pen-and-ink sketches and then present it as a gift to a favoured child.

In this way, she was able to try out her books on real children first but she would borrow the little books back while working on the finished illustrations.

Although born in London in 1866, she married and moved to Cumbria, where she created her famous characters.

'Human settings'

She spent her last few decades extending her farm property and raising Herdwick sheep before her death in 1943, aged 77.

Clive Farahar, an antiquarian book seller who examined the pieces for the Sunday evening show, said: "The story is they came through Mr Swanston's wife's family.

"Her grandfather knew Beatrix Potter's brother who farmed in the Borders quite near to the artist's home.

"A lot of these pre-date Peter Rabbit which came out in 1902, many are sketches and a lot are half finished which doesn't make them any less interesting.

"They show small animals like kittens or mice and rabbits set in human settings doing human things."

Benjamin Bunny

Potter created around 20 well-loved children's tales involving a host of animal characters including Benjamin Bunny, Jemima Puddle-Duck, and Mrs Tiggy-Winkle.

She was born in 1866 in South Kensington, London, and she initially published her first book Peter Rabbit herself before finding a publisher.

Mr Farahar said demand for Beatrix Potter's artwork was intense in Japan and the United States.