"Not much is written about it, because the royal stutterer is a source of embarrassment, " Seidler said.

CNN: Finding words for 'The King's Speech' took decades

"This required going back into the pain and the loneliness and the isolation and frustration of being a stutterer, " Seidler said.

CNN: Finding words for 'The King's Speech' took decades

It took many years for Seidler to allow his mind to recall what it was like to be a stutterer, he said.

CNN: Finding words for 'The King's Speech' took decades

"But as a more mature writer, let me put it that way, when you start looking back on your life, it is easier to go back into the past and therefore, I was able to really put my head back into being a stutterer, which I wouldn't have been able to do otherwise, " he said.

CNN: Finding words for 'The King's Speech' took decades