Frank Humphrey Allen was born in London on March 22, 1896. He studied at Kings College, London, and began his professional career as a surveyor for Estate Agents Knight, Frank & Rutley. He was wounded twice during World War I, suffering all his life from wartime injuries.

Frank Humphrey Allen took his first formal courses in art in the early 1930s at Dartington Hall, Devonshire, working in with Mark Tobey, a forerunner of the American Abstract Expressionist movement. From 1933-1935, he studied at the Chelsea School of Art, when Graham Sutherland and Henry Moore were on the teaching staff.

After leaving the Chelsea School of Art, Frank Humphrey Allen received numerous commissions for posters from the London Underground Transport Board, Guinness, and Plymouth Hoe. During World War II, he participated in the Civil Defense Artists program.

Frank Humphrey Allen exhibited at the August 1943 Artists of Fame and Promise Exhibition at The Leicester Galleries in London. His painting, Thames Ditton, was purchased by the Birmingham City Museum and Art Gallery. He also took part in The London Group show at the Royal Academy in 1944 and in a post-war exhibition of British religious art at the Maison des Beaux Arts in Paris.

In 1949, Frank Humphrey Allen moved from London to Norfolk, finally settling in Norwich, were he would spend the remaining years of his life. He exhibited in the Norwich Twenty show at Norwich Castle in 1968. His art work was also displayed at the William Ware Gallery in London, the Oxford Gallery in Oxford, the Ashgate Gallery in Surrey, and in Norwich area galleries, where a major retrospective show of his work was held in 1969 at the Richard Bradley Atelier.

Frank Humphrey Allen died in 1977 and was survived by his wife, Florence, who continued to promote his art in Norfolk regional exhibitions until her death in 1988.