Combining focus and qualifier

This next snippet gives us the best of both worlds. It has both a long focus and a long qualifier. 

It was a small silver speck of moonlight shining on a polished surface.

Can you see why this noun group is all one thing? It has to do with the first word in the sentence, "It":

It was a small silver speck of moonlight shining on a polished surface.

It was a thing, and that thing was this entire noun group:

[The thing Mr Fox saw] was a small silver speck of moonlight shining on a polished surface.

You'll notice that, in a sentence like this, if we change the noun group, we’re basically changing the whole snippet.

It was a giant collection of marbles rolling down the stairs.

It's entirely reasonable to be confused at this point, because words change their function depending on how they are used in a sentence.

For example, you could make a good argument that "a giant collection" of marbles is not a focus, it's a quantifier: one marble, 100 marbles, a giant collection of marbles—aren't they all quantities?

Sounds completely reasonable! And it's hard to explain why it's not correct. The easiest way to understand is to try playing around with components of the noun group. Which of these sentences sounds wrong?

  • A giant collection of marbles rolling down.
  • A giant collection of one hundred red Sharp Shooter marbles rolling down.
  • One hundred a giant collection of marbles rolling down.

The last one breaks because "a giant collection of" needs to go at the start, where it functions as a focus.

If you're ever confused about word groups, just add and subtract components and move them around, and if you are a fluent English speaker you will very quickly get a sense of what is right and wrong.

It was the news of war they feared.

It was the thumping swagger-loaded sound of rap coming from inside the gymnasium.

Write your own variation. Remember that your focus needs to use the word "of".
Write another one.