Nicky Byrne’s “random conversation” with his sister-in-law Cecelia Ahern ended up inspiring her latest novel.

The popular author and Bertie Ahern's daughter, released her new novel, Freckles, last week.

It explores the idea that you are the average of the five people you spend the most time with.

And the Westlife superstar shared an Instagram photo of himself proudly showing off a copy of Freckles, while shaking Cecelia’s hand.

He said: “So a few moons ago I happened to tell my sister in law Cecelia Ahern this: ‘That you are the average of the five people you spend most time with – so choose carefully.’

“Her crazy creative mind went into overdrive and she went off and wrote her new book from this random conversation!

“What a story – genius! Here she is presenting me with my copy! It’s called FRECKLES.

“Get it, read it because I feel like a really interesting intelligent author helper now and if this becomes a movie I may challenge Spielberg to the best ever at the Oscars!

“Ps – if anyone is struggling for any other ideas just hit me up I’ve got loadsa stuff unused in my brain!”

Deirdre O’Kane was also in on the joke, commenting: "She is one talented lady.

"And for the record, I got a joke idea or two outta that little book you gave me when I turned fifty!!! Text Nicky to 53125."

"Am I due any royalties..?" Nicky responded.

The book’s synopsis reads: “You are the average of the five people you spend the most time with. When a stranger utters these words to Allegra Bird, nicknamed Freckles, it turns her highly ordered life upside down.

“In her current life as a parking warden, she has left her eccentric father and unconventional childhood behind for a bold new life in the city."

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