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Callen Martin

Madeleine Milburn Literary, TV & Film Agency

Submission status
Open
Submission route
Website
Response time
Assume no reply = no after 12 weeks
Last checked
19 days ago

About

Callen is a Literary Agent at Madeleine Milburn, specialising in accessible middle grade (7 and up), young adult and science fiction and fantasy, with an action and adventure focus.

He joined the agency in January 2026 from Bell Lomax Moreton, where he worked as an assistant and then as maternity cover for a senior agent's list before building his own children's, young adult and new adult list. He grew up in foster care and completed Bath Spa University's MA in Writing for Young People in 2019, the first care-experienced person in East Sussex to study at postgraduate level, and began in publishing with placements at Chicken House, Walker Books and Penguin Michael Joseph before working freelance as a submission reader, competition judge, sensitivity reader and manuscript assessor. In 2026 he was named the agent judge for the Times and Chicken House Children's Fiction Competition.

Genres

Children's BooksFantasyMiddle GradeScience FictionThrillerYoung Adult

Looking for

  • middle grade (7 and up), young adult and new adult, and science fiction and fantasy across all genres and formats except verse, poetry and picture books.
  • accessible, high-concept storytelling with real returnability and a clear emotional heart, especially middle grade that gets children, and boys in particular, reading again, with the thrill of gaming or adventure.
  • underdogs, anti-heroes, human and animal or magical-creature bonds, hybrid formats mixing prose and graphic-novel panels, and shorter middle grade for reluctant readers.
  • in young adult, high concepts and strong voice, thrillers with an unexpected twist, smart dystopias, and protagonists who set out to save one thing and change their world in the process.
  • in science fiction and fantasy, unique but accessible magic systems and worldbuilding with a sharp, one-line pitch.
  • he welcomes love stories and romance across everything, especially diverse or queer, and diverse authors throughout.

Not looking for

  • verse, poetry and picture books.

Agency submission guidelines

Submissions are made through the forms on the agency website: Adult Fiction, Non-fiction, or Children's and YA, addressed to the agent who best suits your work. Submissions are not accepted by post or by direct email; only the website forms are read. Format: manuscript and synopsis in Word, 1.5 or double spaced, with only one attachment per form. Adult fiction, and only when the manuscript is complete: an introduction with a one or two-line elevator pitch, up to three comparable books or authors from the past ten years, a compelling blurb and any relevant information about yourself; then a one-page synopsis and the first three chapters or first 10,000 words in a single attachment. The synopsis should tell the story, with spoilers. Non-fiction, sold on proposal, so the book need not be complete: a covering letter introducing yourself and the project, then one document containing a writing sample of about 5,000 to 10,000 words and a proposal. The proposal should cover what the book is about and why it needs to be written, where it sits in the market against similar titles, why you are the person to write it, and a chapter outline with a paragraph or two per chapter. Children's and young adult, only when the manuscript is complete: the same shape as adult fiction: an introduction with an elevator pitch, up to three comparable books or authors, a blurb and relevant information about yourself, then a one-page synopsis and the first three chapters or first 10,000 words in a single attachment. Picture book submissions are not currently considered. Worth knowing: the agency takes up to twelve weeks to consider a manuscript and cannot reply to everyone; no reply after twelve weeks means no. A receipt email confirms arrival. After an unsuccessful submission you may try a different agent after twelve weeks, flagging who you first sent it to. The agency does not accept scripts, poetry or picture books, and agents only ever email from a madeleinemilburn.com address. If another agent requests your full manuscript or offers representation, tell the agency by email.

Agency AI policy

Does not accept submissions of material generated by artificial intelligence.

Links

Other agents at Madeleine Milburn Literary, TV & Film Agency