I don't think anyone here would consider the various parts of Beckett's work that have ended up in a few Iron Maiden tracks to be appropriate without crediting. Except...
http://forum.maidenfans.com/threads/the-beckett-connection.19282/
Let me show you the key phrase:
There you have it. The band was flattered, but they're talking about legal repercussions, as they should, and no Maidenfan blames them for that. I don't remember how that went, but I think that's a fair enough answer for you right there.
How do I see it? A homage. Steve made the music part of something different, and while he should have credited the artist it came from, it's also
right that he didn't represent it as the complete work of the original artist. Which is what I was saying. He didn't say "I made better Beckett". He said "I made Iron Maiden."