DJ Chris Evans is to broadcast from St James's Palace after enlisting the support of the Duchess of Cornwall for his children's short story contest.
Now in its fifth year, 500 words challenges under-13s to write a story about any fictional topic they choose.
Fifty finalists will be invited to the palace in May, where Evans will announce the winners live on Radio 2.
The Duchess, a patron of the National Literacy Trust, will attend a special writing workshop as part of the launch.
The "all-star story laboratory" will take place at Weston Park Primary School, London, on Wednesday.
Authors Frank Cottrell Boyce, Malorie Blackman and Francesca Simon, who are on the 500 Words judging panel, will give advice at the session, which will be filmed and made available to schools across the UK.
Evans said: "We couldn't believe our luck when HRH the Duchess of Cornwall invited us to hold our live on-air final in the stunning surroundings of St James's Palace. She's a supporter of the competition and cannot wait to meet and greet this year's 50 finalists on the day."
The winners will have their stories narrated by a selection of famous names - last year's included Benedict Cumberbatch and Hugh Bonneville.
Children can enter the 2015 contest at bbc.co.uk/500words
Last year, more than 119,000 short stories were submitted.
Susannah Ames won gold in the 13 and under category, for her disturbing story All The Time In The World, set in a distant future, where children's lifespans are determined by a series of tests.
Daniel Martlew took the top prize in the nine and under category. His story, Lost Underground, followed a young boy who became separated from his family on the tube.
Analysis of the 2014 entries found that "minion" - from the movie Despicable Me 2 - was the most popular of the 50 million words submitted by children.
The longest word was "pneumonoultramicroscopicsilicovolcanokoniosis".