Guillonnet was extraordinarily precocious as an artist, entering the studio of Lionel Royer at the age of thirteen and, incredibly, gaining his first medal at the Paris Salon two years later. His glittering youth was continued when he was classed Hors-Concours by the Salon at 21 years of age, which meant his exhibits did not have to be judged by the committee – his six exhibits were hung as a matter of right. In 1901 he won the National Travel Scholarship, which was only awarded every two years and which allowed him to spend a year in Algeria. This proved to be a decisive turning point in his career, because he was greatly affected by the bright light and colours of Algeria, as have many artists before him, notably Delacroix. It was also in Algeria that Guillonnet developed his interest in the painting of ‘half shadows’; the Impressionists had shown that shadows contained contrasting colours and Guillonnet developed their theories.
His early mature style was symbolic, giving otherworldly connections to dreamy beach scenes or figures in a garden. Guillonnet seemed to respond to Charles Maurice’s exhortation of 1888: ‘Since our life is such a terrible affair … unable to provide us with the perfect realization of our dreams of happiness, art will have to deck herself out in the widow’s weeds of joy’.
In about 1915 Guillonnet changed his style to a more strictly descriptive Post-Impressionist expression, depicting figures in gardens. The figures were either passive, as when he painted his wife Emile in one of their gardens, or active and central to the theme of the painting. Another example of Guillonnet’s use of ‘active’ figures in his work is his depiction of figures in fancy dress. He became an Official Painter of the Third Republic, and his classical training and good connections helped him obtain many commissions for work, often of a monumental size. Other than lucrative portrait commissions, many of his important paintings were for the Hotel de Ville of Paris, forty-six panels for the Venezuelan Ministry of Foreign Affairs in Caracas, and the Stations of the Cross in Philadelphia.
The Guillonnet family had two houses, one at Carros in the Alpes-Maritime where they went each summer from 1899 onwards, and the other at Garches, which had a particularly attractive garden. His wife Emilie was a keen gardener, creating a constant source of inspiration for Octave as the seasons changed. In deference to his wife, Octave changed his signature, adding her name. He previously signed either with his full name or just with his initials.
Guillonnet’s paintings are represented in the Paris Museum of Modern Art and many other museums, including the Museums of Luxembourg, Bordeaux, Dijon, and Nantes. He also illustrated various books, including “L’Arlésienne” by Alphonse Daudet.