Paul McCartney - Band on the Run Lyrics Meaning

When I first heard that song I was thinking that McCartney has no ability to write lyrics; that he was looking through a thesaurus to find words that rhyme. But the song makes sense when you consider that he is not really Paul McCartney. Here is some of that song:

Stuck inside these four walls,
Sent inside forever,
Never seeing no one
Nice again like you,
Mama you, mama you.

Why is he singing about being stuck inside something? Is he stuck forever in the role of Paul McCartney, never able to see his own mother?

If I ever get out of here,
Thought of giving it all away
To a registered charity.
All I need is a pint a day
If I ever get out of here.

If he ever gets that where? His role as Paul McCartney? And what will he give away to a charity? The millions of dollars in made in his false life?

It sounds like Paul is saying, "Help! I don't want the money any longer! I want a real life!"

Well, the undertaker drew a heavy sigh
Seeing no one else had come,

Whose funeral is he referring to? Was Paul McCartney's undertaker sad that nobody came to Paul McCartney's funeral? Or was he talking about his own fake death? In order to become McCartney, he first had to arrange a fake death for himself.

One of the amazing aspects of the rumors of Paul McCartney's death is that they have been going on for decades, but McCartney and the other Beatles do nothing to stop it.

What would you do if Internet sites were claiming that you were dead, and that some imposter was pretending to be you? Wouldn't you be tempted to tell those sites to stop it? Some people would threaten the sites with lawsuits if they did not stop making those ridiculous remarks.

Paul McCartney does nothing about the rumors that he is dead. He could so easily put the rumors to rest by giving a sample of his hair for a DNA analysis. His DNA should match his brother and his other relatives. But the Beatles are strangely quiet about these terrible accusations. Why? Do they consider the rumors so ridiculous that they don't want to waste their time with them?