Some people take a lifetime to write a book and even then, getting it published is a whole other story. Others, as it turns out, have two books on the shelf by the age of 14.

Quite an unbelievable feat I know, but one that Finchley Catholic High School pupil Harrison Sansostri, who goes by the name HG Sansostri, has achieved.

“I started to keep a diary in the style of a book, how to make friends and how to survive primary school. My mum and dad read it and said it was really good, I finished it and we sent it off to an editor and then a publisher.”

“I always wanted to write ever since I was little,” Harrison adds, and he was still little when he achieved his goal. He began writing The Little Dudes’ School Survival Guide at the age of 12 and received the first published copy on his 12th birthday.

“The new one is completely different,” he tells me. “The first one was like a guide, so it was fiction and non-fiction at the same time, but this one is complete fiction.”

His latest work, The Chronicles of Derek Dunstable, follows the story of a 14-year-old boy who must take on the role of a hero to survive an apocalypse.

This level of success is quite an unbelievable achievement for somebody of his age once, let alone twice, but Harrison simply loves what he does.

“I enjoy it because it is so free, there are no limits to it. It is just something I enjoy. Sometimes I write in my free time at school in the ICT lounge and people will ask ‘why do you write? Why do you enjoy it? I could never do anything like that.’ “I’m into psychology too. That’s kind of how the first book came about, there’s a section in my book where I categorise people into personalities. I’m good at sussing people out.

“I’m also into acting,” he is quick to add, and it turns out he had achieved incredible things within showbusiness before even putting pen to paper.

“I did Creation when I was seven, which was my first big thing, with Benedict Cumberbatch, Paul Bettany and Jennifer Connelly. I didn’t realise how big of a star they each were when I was seven. Then I did Lord of the Flies at the West End Open Air Theatre.”

I asked if he manages to take drama classes outside of school, on top of his writing and homework and his reply is yet another shining example of his self-governing wisdom.

“I tried to take drama classes at Guildhall. I auditioned and got in but I didn’t particularly like the way it was over-analysed, I thought it was a bit tedious. I just like to do it.”

Perhaps it is simply that easy for Harrison, to just do things, it would explain a lot.

The Chronicles of Derek Dunstable is published by Tiger Publication Ltd. Details: hgsansostri.com

COMPETITION: to be in with a chance of winning a set of the books, please answer the following question: what does the H stand for in HG Sansostri? Then send your answer to: HG book competition, Newsquest London Ltd, Observer House, Caxton Court, Caxton Way,Watford Business Park, WD18 8RJ .