Giuseppe is for once a fully written role and Postlethwaite fully realizes his character. Giuseppe is a very good man although not a perfect one, who is not fully confidant in his son but always wants to try and help him. Before the prison scenes Postlethwaite gives the right amount of heart to the role, and he clearly shows Giuseppe's concern for his son who is growing more and more distant from him. Postlethwaite is brilliant because it is never said from the character that he loves Gerry but Postlethwaite shows through his eyes and his face so perfectly well. A particularly strong scene is when on trial Gerry says he signed the confession because the police threatened to kill his father. Postlethwaite's reaction to this is perfectly tuned and it so brilliantly subtle.
The greatest scenes though do take place in the prison where Gerry and Giuseppe share a cell. I like how the film shows that the father and sons relationship slowly grows closer together during this period. Postlethwaite is perfect in showing Conlon's support for his son, but also strict in that he wants to keep Gerry on the right track. Giuseppe never becomes angry by their misjudgment but he becomes passionate in proving their innocence. Also he perfectly becomes the moral center always saying fighting between the British and Ira will lead to nowhere.
Postlethwaite never becomes one dimensional here, nor does he ever force the good nature of the character, it all is just natural do to his performance. The greatest scene of the performance is the last talk between Giuseppe and Gerry where both actors show the father and son bond in a way that rings true and is truly emotionally effective. His performance is the thing that stood out the most in the film, and when he leaves the film his presence is sorely missed. It is Postlethwaite performance that gives the true power to the film, and he makes the title all the more meaningful.