Now the author is planning a new title which, he says, will reveal all from behind the scenes of the police force and the judicial process.

But Michael admits his life has been on hold for the last year while he awaits a decision from the Criminal Case Review Commission on on whether he has been subjected to a miscarriage of justice.

He was a serving police officer for West Yorkshire Police when he was called out to a domestic dispute in Burley, Leeds, in 1997.

There he was set upon and fought back after being repeatedly punched in the head. Two years later he was charged and convicted of common assault, despite his victim receiving no injuries. He was sentenced to serve four months in prison.

Although he was released after just 33 days, Michael was viciously attacked by inmates at both Armley prison and Ford open prison in Sussex. As a coping mechanism he put pen to paper, resulting in the book A Fair Cop.

The book was a resounding success and is selling at Tesco stores around the country.

But Michael, 36, said he had not been able to get over the idea that he was unfairly convicted after acting in self-defence.

He said: "Since the book came out I've been getting emails from people in the legal profession who have said that, given the evidence laid out in the book, I have been subjected to a miscarriage of justice.

"That has re-sparked the fire in me to have this conviction looked at."

Michael, who lives in Brow Wood Road, Howden Clough, said he will begin writing the transcript for his new book, The Dark Side, next year.

He said his passion for a second book came after readers contacted him, eager to learn what was happening with his appeal.

"I still can't believe how everyone is really interested in the book," he said.

"I keep pinching myself. I have had so much public support, and that means more to me than anything.

"I am still really pleased I did A Fair Cop, but it's always been in the back of my mind that I have unfinished business which needs to get sorted."

* Michael will be giving a talk about progress of his appeal and of The Dark Side at Birstall Library on January 21 from 7pm.

Tickets are £2 (£1 concessions) and must be booked in advance at the library, in Market Street, on 01924 326227.