A major study of what children are reading has found that children start choosing less challenging books when they start secondary school.

The survey of 426,000 children’s reading habits in the UK found that in primary school the difficulty level of the books chosen and the accuracy with which children read them is improved on last year.

But when students make the move to secondary school at age 11, they tend to choose books that have a level of reading difficulty that is lower than their actual age. 

Professor Keith Topping, of the University of Dundee, which carried out the study, said: “There is a marked downturn in the difficulty of books at secondary transfer and this does not necessarily reflect a lack of ability to read more difficult texts.

“It seems that secondary teachers and librarians are not encouraging students to attack more difficult books to a sufficient degree.”

Tricia Adams, director of the School Libraries Association, said that the results reflect the stresses of moving into a larger, more adult environment. 

“The challenges when children go to secondary school are quite traumatic, but they are expected to cope relatively easily. What we’re seeing here is a bit about reading something you know and love and there is nothing wrong with that. Adults do that when we’re under stress; we turn to something we know and love.

“Also, not all schools have a school librarian who are able to say ‘what about this book?’ and promote them a bit more.”

The study also concluded a similar trend for non-fiction. The 15 most popular non-fiction titles in Year 8 were about sport - and seven of those were about football. The biggest hit was a biography of Wayne Rooney.

Overall, the most popular books were the Diary of a Wimpy Kid series, which has also spawned three films. Roald Dahl was the second most read author, while David Walliams, whose seventh children’s book Demon Dentist was the fastest-selling children’s book in the UK last year, made his debut on the list in fifth place.