There are a number of things that Diamond says the English colonists did in this chapter. I will assume that you are asking about what he says they did in Australia at the end of the chapter. I will base my answer on that.
First, let us see what Diamond says they did. On p. 321 in the paperback edition of the book, he says
White English colonists did not create a literate, food-producing, industrial democracy in Australia. Instead, they imported all of the elements from outside Australia.
I completely agree with Diamond.
At first glance, this might seem like a pointless distinction. However, we need to think about why Diamond says this. People tend to argue that the Australian Aborigines were inferior to whites because they did not build a modern society in Australia. By contrast, white English people came and immediately managed to build such a society. This surely proves that Aborigines are inferior.
But this is where Diamond’s distinction becomes important. The English did not create their society using the things that were available in Australia. Instead, they borrowed things from other places. They brought in foreign crops and animals and built their society on those imports. They built the society using things that were not available to the Aborigines. Therefore, it is unfair to say that they actually did better than the Aborigines did.
For this reason, I completely agree with Diamond.