oughtn't to have had it

[Tinkerbell]

Maria knew nothing about the country. She was a London lady born and bred, and she loved luxury, and in that beautiful house looking out on the London Square she had had it; even though it had turned out at her father's death that she really oughtn't to have had it, because there had not been the money to pay for it.

??

[omasta]

Maria knew nothing about the country. She was a London lady born and bred, and she loved luxury, and in that beautiful house looking out on the London Square she had had it; even though it had turned out at her father's death that she really oughtn't to have had it, because there had not been the money to pay for it.

??

Hi! I'm not a teacher.

"...she really oughtn't to have had it"
Here: it = luxury
So, she shouldn't have had the luxury of living in that beautiful house because she had had no money for paying a high rent.