When a woman had put he and Ethel down at the Gulgong Show, Jimmy had gone to the police about it.
The offender was then made to have an apology published in the local newspaper.
And when Mrs Mawbey began putting he and Ethel down at Breelong, Jimmy spoke about taking her to court.
So why did he resort to the Aboriginal customary law of pay back instead?
He may have been pressured into doing so by his full-blood 'uncle' and elder, Jacky Porter.
The word 'pride' is oftened used today by Aboriginal people and appears to be very important to them.
Jimmy's Aboriginal pride had been dealt savage blows by both Mr and Mrs Mawbey, by the former's token payment for 100 unsatisfactory fenceposts and the latter's putdowns of him as relayed by his wife, Ethel.
Jacky Porter may have pointed out that it was not only Jimmy's pride that had been trampled upon, but theirs too as part of his family, and also his 'tribe' (clan) and his nation.
Porter's presence at Breelong may have had something to do with the death of Jimmy's father.
Tommy Governor died in May 1899 and Jimmy's younger brother, Joe, together with a full-blood Aboriginal man, Jacky Underwood, came to visit him in June.
The purpose of their visit may have been to bring Jimmy the news about his father.
They then planned to go to Coonamble to see an 80-year-old 'uncle', Jacky Porter, possibly to do the same thing.
Jimmy invited them to come back and stay with him for a while, and to bring the elder tribesman with them.
Coonamble was roughly half-way between Gilgandra, the closest town to Breelong, and the place where the Castlereagh River joined the Barwon River.
It took about eight days for the return trip on foot.
While Jimmy may have not wanted to rock the boat with the Mawbeys because they were his employers, Jacky Porter would have seen the situation from a very different perspective.
So too would have Jacky Underwood whose real name according to a police telegram was Jacky Underwood Porter.
In 1900 he was said to be aged 38, so he could have been the elder's son or grandson.
Jacky Porter Senior brought with him Jimmy's young nephew, Peter Governor, said to be aged 10 or 11.
One newspaper article said he was actually 15 but small for his age.
Peter may have been the son of one of Jimmy's three older siblings, possibly the eldest, Tommy Jnr, who was no longer living.
Perhaps he had been sent to the old man when his father died, or for initiation.
An elder charged with upholding the respect of his people may have had no hesitation in urging Jimmy to avenge his family, his clan and his country.
In my view, this is the best explanation so far of why the murders occurred.
But it is just speculation, and there were other factors involved ...