By the age of 21, Barclay's work had been published in The Saturday Evening Post, Ladies' Home Journal, and Cosmopolitan.

[1] During World War I, Barclay was awarded a prize by the Committee on National Preparedness in 1917 for his poster "Fill the Breach."

The next year, he designed naval camouflage under the direction of William Mackay, Chief of the New York District of the Emergency Fleet Corporation.

[2][3] During the 1920s and 1930s, Barclay's images were selected for use by art directors for the nation's most popular periodicals including Collier's, Country Gentleman, Redbook, Pictorial Review, Coronet, Country Life, The Saturday Evening Post, The Ladies' Home Journal, Cosmopolitan, and a host of movie magazines.

[2] During the 1930s, he began painting movie poster art for Hollywood studios, including Paramount Pictures and Twentieth Century Fox.

Helene later appeared in magazine advertisements and was so well published with her languid body plastered across the country on billboards, that she was recognized wherever she went.

He also illustrated advertisements for A&P, Eaton Paper Company, Elgin Watches, Humming Bird Hosiery, and Lever Brothers, amongst others.

These products were fabricated out of cast grey metal with a thick bronze plate finish and they retailed for just a few dollars.

[2] In 1944, a year after his death, Barclay was awarded the Art Directors Club Medal, "in recognition of his long and distinguished record in editorial illustration and advertising art and in honor of his devotion and meritorious service to his country as a commissioned officer of the United States Navy."

In March 1943, he told the San Francisco Examiner, "A camera cannot catch the human element of a fight, the sweat and blood and courage our boys expend every time they face the enemy."