Henry Matthew Brock, the son of Edmund Brock, an expert in oriental languages, was born in Cambridge on 11th July, 1875. He was also the cousin of Frederick Pegram. Brock studied at the Cambridge School of Art and by the early 1900s was one of Britain's most popular illustrators. Books illustrated by Brock included The Pilgrim's Progress (1900), The Deerslayer (1900), Last of the Mohicans (1900), Little Women (1904) and Cranford (1912).

Brock also had his work published in several journals including The Daily Graphic, The Humorist, The London Magazine, The Sketch, The Strand Magazine, The Tatler and The Windsor Magazine. He also worked in advertising producing drawings for Johnnie Walker Whisky, Ronuk Polish and Erasmic Soap. Brock also provided 150 watercolour illustrations for Player's Cigarette Cards. G. Montague Ellwood, the author of The Art of Pen Drawing (1927) argued that he had "a flexible technique... that... is more workmanlike than artistic". However he added that he "still had the power to charm in its unfailing dexterity".

During the First World War, Brock became a regular contributor to Punch Magazine in 1916. Brock worked almost entirely in pen and ink and was ideally suited for this work. As one critic pointed out, Brock was "infallible in portraying anatomy and action". Another argued that it was Brock's "flair for drama and action that helped him to achieve considerable popularity as an illustrator of boys' stories."

After the war Brock concentrated on book illustration and successful commissions included The Golden Staircase (1928), All About Me (1928), The Old Curiosity Shop (1932) and Christmas Tales (1932).

Henry Brock died on 21st July 1960.