Dark Lord: Teenage Years wins Roald Dahl Funny Prize

Thompson says he is "chained to a desk, where he spends every day writing for his overlord. Or else".

A fantasy book about a dark lord who is transformed into a chubby teenager has won this year's Roald Dahl Funny Prize.

Dark Lord: Teenage Years by games developer Jamie Thompson won the prize for the funniest book for children aged seven to 14.

He beat other short-listed authors including David Walliams and Frank Cottrell Boyce.

Rebecca Patterson's story about a toddler's tantrums - My Big Shouting Day - won the under-six prize.

She was up against books such as Stuck by award-winning illustrator Oliver Jeffers.

Each winning author collects £2,500 in prize money.

Former children's laureate Michael Rosen, chair of the judging panel, created the competition along with the reading charity Booktrust.

Commenting on Dark Lord, he said: "This is a wonderfully absurd take on beings from another planet or another world and like all books with this theme it makes us think about how odd and crazy we are."

Fellow judge and broadcaster Mel Giedroyc added: "Dark Lord: Teenage Years is a worthy winner - it's funny-clever as well as funny-silly, which in my book is the best combination."

Thompson's book was illustrated by student Freya Hartas - for which it was her first commission.

Schoolchildren were involved in choosing the winners, with more than 500 pupils selected to read the shortlist.

After discussions with their classmates, they picked their favourite book and their votes were combined with those of the adult judging panel to find the winners.