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The 1831 census you can ignore! It basically showed the total males and females at an address - nothing more.
When did John marry in Australia, and what age did he say he was?
Did he arrive as a convict?
If he was born towards the end of the range you gave, he would have travelled at an age of 14 to 20?
So unlikely to have been married in England?
If he was born towards the beginning of your range, then he travelled at an age of 20 to 30?
There is this possibility, from Criminal Registers:
Lancashire County Sessions, 4th April 1848
John Hargreaves, age 15, transported for 7 years, Larceny before convicted of Felony
There are a number of private trees on Ancestry for John Francis Henry Hargreaves.
You would need to ask the owners for any information.