Great Expectations shows through Magwitch that Britain was a far-flung empire that controlled about a quarter of the globe, making it the world's superpower at that time.

Because of the reach of Great Britain across the globe, the convict Magwitch is sent to far away Australia, a British colony. What is most interesting about his sojourn there is that he is able to make a good deal of money, enough to set Pip up as a gentlemen in London, the heart of the British Empire.

This reflected a reality all contemporary readers would have been well aware of: not only was Magwitch able to do well in colonies, but so were many men of higher status. Like Magwitch, these men (though usually more voluntarily) braved the rigors of living in a far-flung outpost in order to get ahead in life. And like Magwitch, they most often brought or sent the money back to England. England was the wealthiest country in the world at this time because of the wealth flooding into it from all corners of the earth. Magwitch was just one of many, many people sending the imperial wealth back home.

Magwitch, as he puts it, lives hard that Pip may live soft, denying himself luxuries so that Pip may have a good life. But what the text remains silent about is the reality that, if Magwitch lived hard, there were native people who lived even harder and saw their resources exploited to finance the lives of fine gentlemen back in Britain.

Magwitch’s situation is an example of imperialism because when he is arrested he is sent to Australia.  Australia was a British colony where many prisoners were sent.  Once there, Magwitch was able to make enough money to send back to England to turn Pip into a gentleman.

Transporting prisoners was a common way of dealing with England's worst criminals. Convicts were routinely taken to the British colonies in America until the Revolutionary War, and after that, to Australia and Tasmania. (enotes etext Reading Pointers for Sharper Insights, p. 4)

Pip is distantly aware of the fact that Magwitch, his convict, has been transported.  In those days it was a life sentence, and to return meant death for Magwitch.  Magwitch being transported to Australia is a comfort to Pip, but he still feels sorry for him.

My comfort was, that it happened a long time ago, and that he had doubtless been transported a long way off, and that he was dead to me, and might be veritably dead into the bargain. (ch 19, p. 103)

In Australia, Magwitch is able to make a good deal of money.  Of course, all of his money goes to Pip.  Yet it is an example of how a person could make a new life in a new land.

“I've been a sheep-farmer, stock-breeder, other trades besides, away in the new world,” said he: “many a thousand mile of stormy water off from this.” (ch 39, p. 215)

Magwitch is proof that not every criminal that was transported was evil.  Some of them might have just needed a second chance.  If they came back to England, they were hanged.