In Northern Ireland, from the late 70s to the early 90s, the IRA killed over 40 alleged informers.

But the man who often found, tortured and sometimes killed these people on behalf of the IRA

was himself an informer, a secret British army agent with the codename Stakeknife.

Who gets to play God? And why me? Why my family?

When lies are still being told to this day, who do you believe?

I wouldn't even know where to start, and I'm with the IRA.

Steakknife.

Listen first on BBC Sounds.

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Hello, today's is a special edition of Open Book dedicated to one of our best-selling children's authors.

Since David Williams, the comedian and actor, first put pen to paper in 2008 with his taboo-busting

The Boy in the Dress, he's become a publishing sensation to rival his hero Roald Dahl.

Since then, he's published 11 books and sold a staggering 12.5 million copies.

Beloved of children and of parents desperate to get their kids reading,

his irreverent humour and ability to reflect social concerns and difficult lives in madcap entertainments has

made him the most successful children's writer of the day.

Nowadays, a father himself, bad dad, his latest number one bestseller, is another

caper set in a poverty-stricken, broken home where a young boy struggles to keep his dad

on the straight and narrow.

Williams began our wide-ranging interview by filling me in on the inspiration behind his latest

literary escapade.

I was intrigued with the idea of a child whose parent goes to prison.

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