At the beginning of this year, we had the pleasure of welcoming Callen Martin to the MMA team as a new literary agent. Callen began his career with internships and placements with Chicken House, Walker Books, and Penguin Michael Joseph, before freelancing across the industry as a submissions reader, writing competition judge, sensitivity reader, and manuscript assessor.
He joined us after working with Bell Lomax Moreton as an assistant, maternity cover for a senior agent, and building his own Children’s YA & NA list.
Meet Callen as we discuss his experience in the industry, the importance of reading for children, and what makes a submission catch his eye.
What was it like getting started in the industry?
Honestly, it was not the easiest or the most straightforward. I was based in Bath, having studied both my undergraduate degree in Creative Writing and my postgraduate degree, the MA in Writing for Young People, at Bath Spa University. After my MA, I managed to secure three internships and work experience placements. The first was at Chicken House in Frome, just down the road from Bath, followed by placements at Walker Books and Penguin Michael Joseph in London.
These experiences were brilliant and gave me a real insight into the industry, but I was still based in Bath rather than London. Despite work in recent years, London has always been the central hub for UK publishing, and being outside of it meant I really had to hustle to get noticed.
Eventually, after a few freelance roles, I landed my first salaried role as a Submissions Coordinator at The Good Literary Agency. It was there that I really discovered agenting and realised it brought together all the things I love most: talent spotting, editorial work, working closely with authors, and championing books I truly believe in. From there I made the move to London and another agency before joining the team at MMA in January 2026, where I am thrilled to work alongside such a passionate and formidable team, shaping the next generation of stories and readers.
What is the most valuable thing you have learnt from your experiences?
The most valuable lesson I have learnt is that voice is everything. Plot, pacing and structure can all be taught and improved with editorial guidance, but voice is something that cannot be manufactured. The manuscripts that make you lean in and keep you reading are the ones where the protagonist and the narrative voice feel alive and authentic.
I have also learnt that the right story can change everything for the right reader. Publishing often talks about trends and markets, but at its heart the industry is about connection. The books that last are the ones that make a reader feel seen, understood, or transported somewhere extraordinary.
How would you define your reading tastes?
I often say I read to escape, not to think. That is the starting point for me and has always guided what I pick up. This does not mean I do not enjoy a story I can get nerdy about. I love worlds and systems I can dive into, whether that is a layered magic system with rules I can learn or a thriller where I am desperately trying to solve the murder alongside the characters.
The key for me is that reading has to be fun first. I am drawn to stories that are immersive, exciting and impossible to put down, not books that feel heavy-handed with lessons or morals. If it is a story I can fall into, with a world that feels as though it continues breathing even after I close the book, then that is a book for me. Middle Grade, YA and Crossover stories that balance adventure, imagination and emotional heart are where my reading tastes really lie.
What book is next on your reading list?
Next on my reading list is Boy Friends by Kai Spellmeier. The tagline alone, Longing to close the gap between boy friends, is something I am already nerdy about. It is my most anticipated YA debut of the year and I am thrilled to have been sent a proof.
What books made you fall in love with reading?
The Story of Tracy Beaker by Jacqueline Wilson taught me to read. I was ten years old and had been in foster care for about six years when my form tutor gave me that book. She recognised that I was a reluctant and struggling reader and handed me the one story that would make me feel seen and understood. That book did not just help me learn to read, it gave me my love of reading.
It also confirmed something I still believe deeply: children’s books are one of the closest things we have to real magic in this world. The right story, at the right time, for the right child, can change everything. Years later a line from The Night Circus by Erin Morgenstern summed that idea up beautifully: You may tell a tale that takes up residence in someone’s soul, becomes their blood and self and purpose.
Those books were formative for me, and they helped me realise that children’s books, from Middle Grade to YA and into Crossover fiction, would always be my heartland. Other tentpole stories for my love of children’s books include: The Hunger Games by Suzanne Collins, Marked by Kristen Cast and P.C. Cast,and There May Be a Castle by Piers Torday – a story that taught me what it is a Middle Grade book could do, perfectly capturing adventure, imagination, humour and emotional depth all at once.
What makes a submission catch your eye?
Above all else, I am always looking for potential rather than polish. I am drawn to children’s books that honour their child or teen point of view, stories that feel authentically written for young readers, with protagonists who feel real, believable and alive on the page.
Voice is what makes me keep reading. A strong premise and hook are important, but if the narrative voice is confident and engaging, and showcases a sense of emotional depth, it will draw me in and make me want to see the story through to the end.
With 2026 being the Year of Reading, I am particularly focused on Middle Grade submissions at the moment. I am looking for the kinds of books that might do for reluctant readers what Tracy Beaker did for me: capture attention, highlight something emotionally true, and make the outside world disappear for an hour or two.
I will never say no to a YA or Crossover title that captures my attention, but at this moment I am prioritising stories that make reading fun and immersive above all else.
How can we get children and teens reading more?
It feels like the million-dollar question at the moment. With literacy levels currently at historic lows, this is something the entire publishing industry is thinking about as the readers of children’s books today are the adult readers of tomorrow.
For me, one of the most important things right now is that books need to be fun. Adventure, excitement, humour and big hooks, the kinds of stories that make a reader want to turn the page. When a child is still building their relationship with reading, enjoyment has to come first. The lessons, the deeper themes, the things that make you think are important often come after a reader has already fallen in love with books.
Books today need to compete for attention with everything else young people are consuming, from social media and gaming to streaming and video content. That means stories must be immersive, exciting and impossible to put down, told in accessible ways that encourage, not discourage, a love of reading.
What do you think is the most important part of reading for children and teens?
For me, it is connection and enjoyment. When a child discovers a story they genuinely love, reading stops feeling like homework and starts feeling like an adventure. That moment, when a book captures their imagination and makes them forget about everything else, is incredibly powerful.
I think sometimes we underestimate how important joy is in reading. Children do not fall in love with books because they are being taught a lesson; they fall in love with books because they are funny, thrilling, magical or full of adventure. Fun is the gateway to reading. Once a child falls in love with books, the lessons take care of themselves.
And when that happens, when the right story reaches the right reader, that love of reading can last a lifetime.
