The Martha Mills young writers’ prize has opened for entries on the theme of “A Secret”.

The competition, run by the London Review Bookshop, invites 11- to 14-year-olds living in the UK to submit up to 500 words of any type of prose – such as a fictional story, a piece of schoolwork, or a diary entry – based on this year’s theme.

The prize was set up in memory of the daughter of Merope Mills, editor of the Guardian’s Saturday magazine, and Paul Laity, an editor at the London Review of Books. Martha, who was a keen writer, died in 2021 aged 13.

Philip Pullman, author of the His Dark Materials trilogy, joins Mills, Laity and the London Review Bookshop’s Gayle Lazda on this year’s judging panel.

“We’re so pleased to be launching the second year of the prize, and even more thrilled to be announcing Philip Pullman as a judge. Like a lot of children her age Martha ripped through the His Dark Materials series, rereading them until the pages came loose,” Mills and Laity said.

Three winners will each receive £200 as well as a selection of books and “a special souvenir”. They will also be invited on an expenses-paid trip to a ceremony at the London Review Bookshop. A selection of entries, including the three winners, will be published in a pamphlet.

Entrants are encouraged to take the theme of “A Secret” in any direction. “It could be a story of a secret between friends, or a tale of spies or detectives. Or you could write about a secret that has affected your own life, or the life of someone you know,” said prize organisers.

“We are looking for writing that is lively, unusual or otherwise original,” said the judges. “It doesn’t have to be perfect or finished – we want to see the work that you’re most proud of or most excited about. Don’t worry if you haven’t written much before or don’t know if you’re a ‘writer’”.

Last year’s winners were Izzy Cooper, Flynn Alexander Hampson and Mabel Swift, whose submissions can be read in the 2023 pamphlet.

The closing date for entries is 19 July. More details on how to enter can be found on the London Review Bookshop’s website.