The creator of the best-selling Alex Rider spy novels has accused fellow children ’ s author David Walliams of dumbing-down fiction and failing to ‘ challenge ’ young readers . Anthony Horowitz said books by the comedian – who was the UK ’ s top-selling children ’ s author last year – are ‘ witty and entertaining ’ but nowhere near ambitious enough . The 59-year-old novelist and screenwriter singled out Walliams ’ Gangsta Granny for criticism , as well as the Diary Of A Wimpy Kid books by author Jeff Kinney . Scroll down for video . Author Anthony Horowitz ( pictured right ) said books by comedian David Walliams ( left ) – who was the UK ’ s top-selling children ’ s author last year – are ‘ witty and entertaining ’ but nowhere near ambitious enough . He insisted that such writers should challenge their young readers and not be ‘ afraid of powerful stories or serious ideas ’ . He suggested they should follow the example of authors such as John Green and ‘ write up for children , not down to them ’ . Green ’ s book , The Fault In Our Stars , tells the story of two teenagers who fall in love while they are both dying of cancer , and was the top-selling title of 2014 , with more than 870,000 copies sold . Horowitz , who is also the principal writer on the ITV period detective drama Foyle ’ s War , singled out Gangsta Granny , with its breaking-wind jokes and a character who perpetuates the myth that children ‘ automatically dislike reading ’ . Writing in the Times Educational Supplement , he said he was troubled that children ’ s books ‘ seem to have come full circle ’ . Walliams made over £7million in 2014 from book sales including The Boy in the Dress and Demon Dentist . He added : ‘ To some extent , narrative fiction was reinvented by JK Rowling – it ’ s hard to believe that children weren ’ t challenged by books that stretched to 760 pages – and a phalanx of writers crested on her success : Michael Morpurgo , Philip Pullman , Jacqueline Wilson , Malorie Blackman , Eoin Colfer , Darren Shan ... and me . 'Today it is Jeff Kinney and David Walliams who top the bestseller lists , with books that are witty and entertaining but nowhere near as ambitious. ’ He added : ‘ Speaking personally , I was a little sad when , in Walliams ’ Gangsta Granny , we were told that among the old woman ’ s vices , which included dribbling and farting : “ Her house was stuffed full of books and she was always trying to get Ben to read them , even though he loathed reading ” . ’ Horowitz said ‘ the idea that children automatically dislike reading or that books belong to a more fusty , ancient generation is patently absurd ’ . His Alex Rider books , the first of which was published in 2000 , have been ‘ brightly re-jacketed ’ , and are ‘ as popular as ever ’ . They have sold 19million copies in 30 different languages , he pointed out . Horowitz said : ‘ Quite recently , I addressed an audience of largely unpublished writers in New York and I stand by the advice that I gave them . ‘ Write up for children , not down to them . We don ’ t need to be afraid of powerful stories or serious ideas . The audience is there. ’ Walliams last year made more than £7million from book sales . The 43-year-old Britain ’ s Got Talent judge had four books in last year ’ s top 50 bestsellers list . His latest book , Awful Auntie , sold more than 500,000 copies last year . The success of his books , which also include Ratburger and Billionaire Boy , has also been boosted by television adaptations , such as The Boy in the Dress , which starred Walliams , Meera Syal and Jennifer Saunders , and was shown on the BBC at Christmas .
Author Anthony BBC has accused David Walliams of dumbing down . Claims Walliams fails to challenge young readers with unambitious books . BBC argues authors should not be afraid of 'powerful stories or ideas '