I'm the bearded man in the green pullover. I wrote the book ("The Prisoner List") on which Danny Roberts and Kate Owen have based this remarkable film, and the central character in the story is my father.

I was stunned by the sheer power of this docudrama the first time I saw it, and I have watched it countless more times since. On each occasion the impact is at least as strong as the last, but I notice something more with each successive viewing - the writing, the acting, the photography, the animations, the music.

I would not have thought it possible that a film of this length could cover so much and convey such emotion. Not a moment of the 17 minutes is wasted; even the closing credits pack a powerful punch of their own.

Kate (producer) and Danny (film and editing) have done a tremendous job and were fantastic when I met them for the interview scenes. This film is testament to their skill, professionalism and attention to detail.

Even the pages of the replica record book that Danny reproduced manually for the dramatised scenes are barely distinguishable from those of the original compiled by my father.

My father would probably have been embarrassed to see himself as a character in a film, but he would have loved the film itself. He would also have been pleased to know that two people born more than 70 years after him were interested enough in these events to make a film of this kind.