Even as a child, artist Lucian Freud’s talent shone through in crayon sketches and pencil drawings, a fact not lost on his mother, Lucie, who lovingly kept them safe even as the family fled Nazi Germany in 1933.

Now this remarkable collection of 47 sketchbooks of 800 drawings, as well as the 162 drawings produced during Freud’s younger years, have gone on display for the first time at the National Portrait Gallery alongside a newly-discovered unfinished self-portrait from the 1980s.

Lucian Freud Unseen, which runs at the gallery until 6 September, comes five years after the artist’s death in July, 2011.

The collection was donated to the nation by the Freud family in a £2.9m gift to the gallery in lieu of inheritance tax.

Born in Berlin in 1922, Freud was the son of Ernst L Freud and the grandson of psychoanalyst Sigmund Freud. He was also the younger brother of Stephen, and disgraced broadcaster and politician Clement Freud.

The exhibition shows the childhood drawings in vivid colours reflecting Freud’s early passions for birds, trees and horses, which he continued to draw throughout his life.

His mother, after whom Freud was named, first encouraged her young son to draw and paint after discovering he was dyslexic.

Self-portrait (fragment) by Lucian Freud, c1980s

Self-portrait (fragment) by Lucian Freud, c1980s

Thanks to Lucie, who collected and annotated the drawings with their time and place, we can see the development of his extraordinary talent from early childhood onwards.

Some depict Freud as a child with his family and reveal much about the intimate life of the Freuds and their years as refugees adjusting to life in England.

As the favourite of Lucie’s children, the young boy was indulged. With her strong, rather severe features, she resembled him closely and his portraits of her are among his best.

The pair were close and Freud was a devoted son, despite his later reputation for misogyny and philandering.

Landscape with figures by Lucian Freud, c. 1930s

Landscape with figures by Lucian Freud, c. 1930s

Lucie was devastated when her husband, Ernst, died in 1970, as her whole life had revolved around him.

This led to a situation where, after his father’s death, Freud would collect his severely-depressed mother every morning and use her as his sitter in order to keep his eye on her.

Under his loving care, Lucie lived on until she was over 90. The display features an amusing letter written by Freud to his mother in a childish hand from post-war Paris, giving us an intriguing glimpse into their complex relationship.

Another highlight in the show is a drawing of the writer and Irish Guinness heiress Lady Caroline Blackwood, who became Freud’s second wife. This item relates to the artist’s earlier 1952 masterpiece Girl in Bed, which was painted in the Hotel La Louisiane while the couple were living in Paris.

Self-portrait with lamp and notes in Sketchbook by Lucian Freud © The Lucian Freud Archive

Self-portrait with lamp and notes in Sketchbook by Lucian Freud © The Lucian Freud Archive

They eloped a year later, ignoring furious disapproval from Caroline’s family, when she was aged just 22. The loaned canvas can be seen in the National Portrait Gallery’s 20th-century collection display on the first floor.

This oil painting’s painstakingly detailed brushwork, reminiscent of Dutch Old Masters, tenderly captures Caroline’s striking, natural beauty. You can almost see the reflection of Freud in Caroline’s soulful, saucer-sized eyes. The pair’s stormy marriage was dissolved in 1958 and she went on to marry two other fiery geniuses, the composer Israel Citkowitz and American poet Robert Lowell.

Girl in Bed by Lucian Freud, 1952 ©The Lucian Freud Archive Bridgeman Art Library

Girl in Bed by Lucian Freud, 1952 ©The Lucian Freud Archive Bridgeman Art Library

Lowell happened to be clutching this iconic portrait of Caroline when he had a sudden heart attack and died in a New York taxi in 1977.

Another gem on display is Freud’s sketch for the cover of Hideous Kinky, an enchanting novel written by his daughter, Esther, which was made into a film starring Kate Winslet.

It was based on the true story of Esther’s childhood adventures in Morocco with her older sister, Bella, after their free-spirited mother, Bernandine Coverley, another great love of Freud’s life, moved them to Marrakech in 1967.

Born to Irish-Catholic parents, Bernandine became a writer, poet and passionate gardener. Although she split up with Freud after her daughters were born, they remained on friendly terms. She died from advanced cancer just four days after Freud passed away.

Rounding off the exhibition is Freud’s previously-unseen self-portrait, thought to have been painted when the artist was in his 60s. It demonstrates his technique of beginning a portrait in the centre of a face, usually with an eye, and then working outwards.

Although Freud used himself as a model throughout his life he found it challenging and in 1992 remarked: “The way you paint yourself, you’ve got to try and paint yourself as another person. Looking in the mirror is a strain in a way that looking at other people isn’t at all.”

• Lucian Freud Unseen runs until 6 September at National Portrait Gallery, St Martin’s Place, London. Admission free. Details: 0207 306 0055 or www.npg.org.uk

A book accompanying the exhibition, published by the National Portrait Gallery, is available now, priced £18.95 (hardback).