Picasso's doodles and scribbles up for auction

It is not every day that 100 unknown Picassos go on sale. Just off the Champs Elysées in Paris today, there will be an auction of drawings, doodles and scribbles by the father of modern art, which range from the banal to the disturbing to the charming.

There are florid notes, scratched in Pablo Picasso's handwriting on scraps of paper with hurried messages like "I'm in the restaurant" – with an estimated price of €1,500 (£1,045). There are five, signed copies of Picasso's Communist Party membership card from the mid 1960s – with estimated auction prices of €500.

There are also previously unseen sketches and cut-outs by the Spanish artist, some beautifully child-like, others in his familiar Cubist style. All were collected over a period of 33 years by a relatively unknown but very important woman in Picasso's life. The woman, Inès Sassier, was never Picasso's lover or mistress or wife. She was, variously, for more than three decades, his friend, adviser, house-keeper, cook, nanny, model and confidante.

Picasso's daughter, Maya Widmaier-Picasso, describes Inès Sassier as "our fairy Godmother...more than a relative, more than an aunt, more than a grandmother ... Inès idolised my father. My father adored Inès".

The collection has been put up for sale today at Artcurial, in the Rond Point des Champs Elysées, by Mme Sassier's son, Gérard Sassier.

The 150 drawings, photographs, mementoes, and a handful of signed lithographs, are expected to fetch up to €444,000 and possibly far more.

Several of the works were drawn by the Spanish master for Gérard when he was a small boy, living alongside Picasso's own children in his studio at the Rue des Grands Augustins close to the Left Bank of the Seine.

There is a stunningly beautiful coloured pencil sketch and collage of a boy with a bicycle, dedicated "Pour Gerard" (estimated auction price €40,000).

There is a humorous cut-out of a little boy peeing, with a cheeky (literally) rear view on the reverse side (€15,000). There is a bold, but disturbing water colour of a monkey riding a circus horse.

Many of the drawings recall images which are familiar from Picasso's best-known works, including a minuscule doodle of a glum-looking horse (€4,000) and a series of studies for elongated women's eyes (€6,000).

Biographies of Picasso have often dwelt on his wives and mistresses and many girlfriends. There was a moving photographic tribute recently to Picasso's pet dachshund, Lump.

Little attention has previously been given to the Italian-born, Inès, who appears to have been much more than a house-keeper, or nanny, without ever – as far as is recorded – succumbing to Picasso's legendary sexual charm. Picasso first met Inès in 1936 when she and her sister worked in the hotel where he stayed at Mougins, near Nice. Picasso was living in some squalor, in Paris, sometimes alone, sometimes with his three children. The painter was approaching the height of his fame, and about to undertake one of his most celebrated works of art, Guernica.

Combining fatherhood and the reinvention of art was not easy. According to his daughter Maya, "the housework was seldom performed as it should have been."

In 1937, the painter invited Inès and her sister, Marinette, to come and live on the floor below his studio in the Rue des Grands Augustin as temporary housekeepers. Inès stayed on, got married to a young Parisian, Gustave Sassier, and became a kind of surrogate mother to Picasso's children. During the war, when food was scarce, Inès performed culinary miracles with hardly any ingredients.

When the painter moved to the south coast in 1961, Inès became the curator and guardian of the – by now celebrated – studio in the Rue des Grands Augustins. She accompanied Picasso's children to his villa in the south each summer.

Mme Sassier kept many items that others might have thrown away. The auction includes elaborate notes bearing messages like "Je serais ici à 7 heures" (I'll be back at 7). There is also an envelope addressed to Inès at the Rue des Grands Augustin in 1957 containing Picasso's signature.