He was one of the most prolific authors in entomology, and stirred controversy during his later life as his publications resulted in a huge number of junior synonyms.

Between June 1848 and late 1873 Walker was contracted by John Edward Gray Director of the British Museum to catalogue their insects (except Coleoptera) that is Orthoptera, Neuroptera, Hemiptera, Diptera, Lepidoptera and Hymenoptera.

Born into a wealthy and educated Quaker family, Francis spent the years 1816 (when he was seven years old) to 1820 (when he was eleven) in Switzerland at Geneva, Lucerne and Vevey where the family party was joined by Madame de Staël, the poet Lord Byron and some Swiss naturalists gathered around Nicolas Théodore de Saussure.

He lived at Arnos Grove and at 49 Bedford Square which housed the collections of the Entomological Club founded in 1826 by George Samouelle and Edward Newman among others.

In this respect, however, he was no worse than many entomologists of his time; what makes for the more common occurrence of Walker's taxa in synonymy is the sheer volume of his work.

An unsigned obituary began "More than twenty years too late for his scientific reputation, and after having done an amount of injury almost inconceivable in its immensity, Francis Walker has passed from among us".

Fortunately, many of his descriptions of Darwin's insects will endure because they were of little-known groups from little-worked regions and most of his types are still in the British Museum (Natural History).