The measurements, taken from the model Giacinto were for Aglaia to construct a leather subarmalis for the illustrations to the illuminated manuscript of Morris's translation of Virgil's Aeneid. As a bookbinder she was skilled in the use of leather and was capable of making the costume which Burne-Jones required.
Aglaia Coronio (née Ionides; 1834 – 20 August 1906, Greek: Αγλαΐα Κορωνιού) was a British embroiderer, bookbinder, art collector and patron of the arts. Of Greek descent, she was the elder daughter of businessman and art collector Alexander Constantine Ionides, who had immigrated to London from Constantinople (present day Istanbul) in 1827. Her older brother was Constantine Alexander Ionides (b. 1833); her younger siblings were Luca (b. 1837), Alexandro (b. 1840) and Chariclea (b. 1844). Aglaia became a confidante of William Morris and a friend of Dante Gabriel Rossetti. She and her cousins Marie Spartali Stillman and Maria Zambaco were known among friends as "the Three Graces", after the Charites of Greek mythology (the youngest of whom was also "Aglaia").
The most likely answer is that the compiler was Aglaia Coronio or one of her relations, possibly her daughter Calliope. A member of the large Anglo-Greek family of Ionides which figures so prominently in the annals of Victorian art (see lot 572), Aglaia was a close friend of William Morris and might well have owned caricatures of him. It is interesting that some show him doing cartwheels and handstands (figs.3 & 4) while one shows him in his bath, since Luke Ionides, one of Aglaia's brothers, recalls in his privately printed Memories (1925) that he 'had a set of [Burne-Jones] caricatures of [Morris] doing catherine wheels in Cavendish Square, and another at the Turkish bath, where we had gone together'. These drawings may be the ones in question. Aglaia was also close to Burne-Jones. Her 'perfect taste', Lady Burne-Jones recalled, 'had helped him a hundred times by finding fabrics and arranging dresses for models' (Memorials of Edward Burne-Jones, 1904, II, p.196). The album contains a letter which bears this out. 'Dear Aglaia', he writes, 'I have measured Giacinto - here are such measurements as an unskilled tailor can make - I have measured round him - and down him - is it enough? also how kind & helpful you are - & I am ashamed to give you such trouble'. Giacinto must have been one of the Italian models who were so much employed by Victorian artists, and there follows a diagram of his body with measurements for a 'leather coat', apparently in the Greek style. The many other sketches of dresses and accessories which the album contains may also have been made to help Aglaia make studio properties. One sketch is on a piece of paper inscribed 'wait for answer/Mrs Coronio', another is on writing paper headed 'I Holland Park, W'. This was the house of her brother Alexander, who created there one of the great 'aesthetic' interiors of the day, Burne-Jones being among the contributors. Aglaia herself lived next door at 1A.