The Long Good Friday is about a gangster named Harold Shand who has eliminated all rivals, hob knobs with a portion of London society, and has big visions about deals that will make London great again. However, just mistaking this as just a gangster film, and not about much more, is a huge mistake.
On one level, Shand represents the state of England. Like England, he is tired of the Americans always having the upper hand. He is arrogant, brash, and at the same time tired of being put down and treated as second-class (like the United Kingdom at the time). He knows that there is the lure of an united Europe and the potential profits are tremendous. .
On the next level of interpretation, the Irish issue always somehow shoves it's face into the picture. That is the "iceberg" that Shand has unwittingly hit. His loyal friend (Paul Freeman) from long ago (the Frenchman in Raiders Of The Lost Ark) has accidentally had a deal with some wing of the IRA in Belfast that cost him his life. The audience gasps at the word IRA, because now he has to confront a powerful and well organized rival. As one of Shand's associates says when Shand attempts to confront a group of IRA in London, "They are political. These are fanatics!".
On another level, the reality of the movie is that Shand's gang is slowly bumped off and his prized pub blown up, Shand slowly starts to find out what really is the cause of the vendetta against him. The movie is also a detective's mystery. Shand becomes Poirot for most of the movie - trying to figure out who really is out to get him. He is as clueless as the audience is.
On the next level, this movie is called The Long Good Friday, because it is also a religiously symbolic movie. It takes place on religious holiday. It is about a man who thinks that he is righteous, accidentally kills perhaps his most loyal lieutenant, and then thinks he can cover it up and redeem himself by committing himself to focusing on revenge. But, he can't redeem himself. He has doomed himself by his own sins. It is too late. So,the movie is really about a man who lost his soul in his lust for power, and now deludes himself that he can hold on and justify his power for eternity. However, the unknown is sealing his fate. Isn't the the heart of what Christianity is all about?
Lastly, the ending. In the end a young Pierce Brosnan is holding a silencer to him as he gets into a car. The look on Shand's face is the last minute of the film. He says nothing, but you can see every thought and emotion on his face. The only thing that we know about the young assassin played by Brosnan is the credits say he is an "Irishman". But that's all we really know. He is probably a member of a rogue element of the IRA that Shand could not possibly account for. However, I think that this is part of the mystery of the movie. All the viewer knows is that some Irish are out to get him. You never really learn their true motives, and who they really are.
This movie has a lot of mystery and depth to it. We don't know what it is all about. All we know is that somebody wants to get the most powerful mob boss in London. As I have said, there is a reason the film is entitled "Good Friday". It is about a man who confronts his own soul and loses. His bitterness, rage, and ambition cause him to kill lieutenant accidentally with the broken glass of a wine bottle. I don't think that Shand intended to kill his lieutenant named Colin. I think he wanted to teach him a lesson, but he is horrified to see that the bottle he wielded broke and slashed up his lieutenant. You can tell by the look of horror in Shand's face that he is even in disbelief of what rage can do to him.
Instead of walking away from his life of crime, Shand is too proud and arrogant. He thinks that he can make up for his brutal accidental murder of Colin by being righteous in revenging himself on his enemies. In this gruesome scene, life's fragility is shown. And even the cold-blooded Shand is horrified by his sin and his lack of control of his anger. And then, like a delusional sinner, he thinks that he can redeem himself by finding out exactly who is out to get him. He thinks that by getting his enemies he will finally find true peace. However, he deludes himself, and in the end he is doomed to die at the hands of the young assassin (Brosnan).
In the end, he was undone by his own ambition and foolish pride. And only then does Shand see the full extent of his life of greed and lust. Shand sees that all along he deceived himself into being greater than he really is, and that he could actually escape his own fate in the end. As the film draws to a close you can see that Shand is now resigned to be punished for his sins.