The sketches, stylistically typical of the great modern sculptor, have come from the family of the late antiques dealer Eila Grahame, who traded from a shop in Kensington Church Street for many years and who died in 2009.
Martin Millard, a Cheffins director of fine art, said: “We found these drawings buried under piles of dust-covered antiques, paintings and drawings. They have never before been seen by the public and we are expecting them to be of interest to museums and galleries around the world as well as individual collectors.”
The pencil sketches, estimated at £40,000-60,000, are on two sides of the same sheet of paper and are titled Têtes (recto) and Nu debout (verso).
With the paper signed Alberto Giacometti 1947, Cheffins confirmed the authenticity of the sketches with the Fondation Alberto et Annette Giacometti, which has included them in the artist’s catalogue raisonné.
Cheffins previously sold the bulk of the Eila Grahame collection in December 2016. The consignment raised £577,000, with the top lot being three Doccia porcelain dishes from c.1740-45 that sold for £70,000.