Eila Grahame, who traded from a shop in Kensington Church Street for many years, died in 2009. Cheffins previously sold the bulk of her collection from her London property and Suffolk cottage, as well the items that she kept in storage, in December 2016.
The consignment raised a total of £577,000 with top lots being an Antonio Chichi cork model of the Temple Della Sibilla in Tivoli that made £53,000 and a group of three Doccia porcelain dishes from c.1740-45 that sold for £70,000.
The Giacometti sketches are stylistically typical of the great modern sculptor. They appear on two sides of the same sheet of paper and are titled are titled Têtes (recto) and Nu debout (verso).
The signature of Alberto Giacometti on the double-sided drawings being offered at Cheffins.
With the paper signed Alberto Giacometti 1947, the auctioneers confirmed the authenticity of the drawings with the Fondation Alberto et Annette Giacometti who have included them in the artist’s catalogue raisonné.
Director at Cheffins Martin Millard 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 sketches will be offered in Cambridge with an estimate of £40,000-60,000.
