Trebilcock was a successful portrait painter who worked with an eye to the old masters of portraiture. His commissions came from the society world and universities; and his preferred models were attractive young women, elegantly attired.
Trebilcock graduated from Oak Park and River Forest High School in 1920, and then attended the University of Illinois where he studied chemistry (1920-22). Returning to a childhood interest, he turned to the study of art that he pursued at the Art Institute of Chicago (1922-24) under Leopold Seyffert.
In 1925 Trebilcock won the Martin B. Cahn prize for Self-Portrait in the 38th Annual Exhibition of American Paintings and Sculpture at the Art Institute of Chicago. The following summer was spent in England where he copied old master portraits, including ones by Velasquez, Rembrandt, and Van Dyck, and painted London society and local types. One of the works he did during that visit, Portrait of an Old London Cabman, was purchased by the Albright Gallery, Buffalo.
Upon his return from England he exhibited many of the works done there, as well as works done in Chicago and New York, at the Grand Rapids Art Gallery, Grand Rapids, Michigan (December 1925), and at the Chicago Galleries (May 1926). Also in 1926 he exhibited five works in the 30th Annual Exhibition by Artists of Chicago and Vicinity. In that exhibition he won the William Randolph Hearst prize for Svojrazy Kabat, a portrait of a young woman wearing a sumptuous fur coat which is referred to in the title of the painting.
Also in 1926 he won first prize for a portrait of the elderly Mrs. Mary Virginia Ellet Cabell at the first annual exhibition of paintings by artist members of the Chicago Galleries Association. In 1928 Trebilcock showed fourteen pictures at the Art Institute of Chicago in an exhibition of seven local painters. Concurrently with that exhibition, his portraits were shown at the Robert C. Vose Galleries in Boston.
In 1928 he also won the Mr. and Mrs. Frank G. Logan medal at the exhibition of Artists of Chicago and Vicinity at the Art Institute for a Self-Portrait Portrait of a Painter. This work is now part of the collection of the Art Institute of Chicago. That same year sixteen of his recent portraits were published by I.R. Koen and E.L. Heitkamp.
In 1929 he won the William R. French gold medal at the 42nd Annual Exhibition at the AIC for Chiarina, done in a style reminiscent of the Italian Renaissance masters.
In 1929 Trebilcock married Amaylia Chiarina Castaldo, of New York City, a painter of children's portraits. Trebilcock often took his wife as a subject for his portraits. One of the most outstanding of these, a full length formal portrait with his wife in evening dress, done in a long narrow format, was exhibited in the Annual Founders' Exhibition at the Grand Central Art Galleries in 1931 and hung next to Sargent's portrait of the Countess of Lathom.
In 1931 after returning from a trip to Italy, Trebilcock exhibited twenty-five works at the galleries of Carson Pirie Scott & Co., Chicago. Also that year his work Two Women was awarded the First Hallgarten Prize at the NAD; this work was later exhibited at the Carnegie International Annual Exhibition in 1936.
In 1933 an exhibition of his portraits was held at the Grand Cental Art Galleries. In 1937 his work Lelia was awarded the Municipal Art League Prize for portraiture at the 41st Annual Artists of Chicago and Vicinity Show at the Art Institute.
Numerous portraits by Trebilcock are part of public collections including: Portrait of Dean Shailer Mathews (1926), Divinity School of the University of Chicago; Portrait of Mrs. John A. MacMillan, The Dayton Art Institute; Portrait of George A. Joslyn (1932), the Joslyn Memorial Art Museum in Omaha, Nebraska; Portrait of President Roosevelt (1933), commissioned by the president's law classmates, Columbia University; Portrait of Dr. Rush Rhees (1934) and Portrait of George Eastman (1934), the University of Rochester.
Trebilcock maintained studios in both New York and Chicago. Trebilcock was nominated to the NAD by Leopold Seyffert.
