The images by Chagall, the pioneer of modernism whose paintings sell for up to £10 million, are contained within the pages of a notebook that once belonged to Bella, whose sudden death at the age of 49 devastated the artist.

After his wife died in 1944 from a viral infection, the grieving Chagall kept her notebook, which he illustrated for the next 20 years, sketching on the blank pages and surrounding Bella's writings with colourful and moving posthumous portraits of her and the two of them together.

In one sketch, Bella is depicted in a patterned dress with a bowl of fruit, while another drawing shows her with dark circles around her eyes, possibly depicting her final illness.

The couple also appear together throughout the notebook, with Chagall recalling their wedding day in 1919 in a pen-and-ink drawing of them as bride and groom.

On the opposite page is verse from a popular Second World War French song – "Chant des Partisans" – that Bella had translated into Yiddish in her notebook.

In perhaps the most moving image, Chagall, with a blue face and melancholy expression, is seated at his easel, contemplating a red painting of himself and Bella, one hand reaching out to touch the canvas with his other hand held to his heart.

Another etching captures the artist's vivid imagination, featuring a walking double bass with a flowing mane of hair in the shape of a violin, and a collection of mermaids.

The 85-page notebook, which Chagall illustrated between 1944 and 1965 while he spent time living in New York and the south of France, also includes several self-portraits.

In one, Chagall appears as a drinker, seated next to a bottle labelled with his initials; in another he depicts himself as a satyr with palette and brushes. Chagall, who was Jewish, was also famous for his religious iconography and the sketch book features Christian and Jewish imagery, including a series of portraits of King David and a sketch of angels.