A general counsel to the federal Attorney-General, dean of law at Melbourne University, monarchist, author of legal textbooks: it was a long and distinguished professional life.

What Mirabella did not mention, it is now alleged, and what she had never admitted even to her family, was that Howard, 40 years her senior, was also her live-in lover for five years in the late 1990s. Nor that she had received gifts from him valued at well over $100,000 to help her election to Federal Parliament in 2001. Nor, allegedly, another substantial sum to buy her Wangaratta farmhouse in 2007.

Nor did she say that she was the executor of his will and, his family believes, its sole beneficiary. If this is the case she stands to inherit Howard's $1 million house in a prime street in the Melbourne suburb of Carlton.

Neither did she say that Howard had lived for nearly a year in a cottage at the back of Mirabella and her husband's country farmhouse as his mental and physical heath deteriorated, he grew incontinent and paranoid, and eventually had a fall which nearly killed him.

These matters are now part of an acrimonious dispute with Howard's daughter, Lesley, and son, Mervyn. Hostilities were suspended earlier this month as they stood metres apart around a gingko tree at the cemetery to remember him and inter his ashes. Now the Howard family wants answers, or they will go to the Supreme Court to challenge his estate.

Mirabella declined to answer questions from the Herald, saying only: "It is less than 12 days since Dr Howard was buried and no application has been made to obtain grant of probate of his will. There is no public interest in denigrating the memory of a private man.''

This story began in 1994 when the young solicitor Sophie Panopoulos met the man she described in her maiden speech in the House of Representatives as a man whose ''intellectual ability and integrity'' had inspired her.

By the following year they were romantically linked and living together - she, born in 1967, at the start of a legal career and he nearing the end of his. Despite raised eyebrows, Panopoulos was accepted into the families of Mervyn and Lesley Howard. In 1995 she travelled with Howard to visit Mervyn, a British-based fund manager who helped administer the business interests of the sixth Duke of Westminster.

But Panopoulos's family and friends were not allowed to know about her relationship with Colin Howard. For six years she and Howard visited Lesley and her family on Christmas morning before Colin returned to their shared house in Carlton and Panopoulos went to see her parents, who were blissfully ignorant of her living arrangements.

In 2000, Panopoulos moved to Wangaratta to seek Liberal preselection for the northern Victorian rural seat of Indi. Howard was an enthusiastic campaigner on her behalf. He loaned her his car to campaign in and he paid campaign expenses to the tune of $100,000 to help her win.

He did so because he was proud of the woman he described in November 2000 as starting out a ''brave but stranded young political fringe-dweller'' who, with ''a touch of political genius'', had become a ''Liberal legend''. But she had also promised him that she'd employ him in her electorate office should she win the vote.

But soon after the election win in 2001 they began to grow apart. At 74, Howard was finding the drive between Melbourne and Wangaratta difficult. And, she is alleged to have told him, her backbencher's staff entitlement was not sufficient to employ him.

In 2002 Panopoulos met and formed a relationship with another man. Howard went back to his life. Always socially awkward, his circle shrunk to his two children and the owners of his local restaurant, Abla's.

In 2006, Panopoulos married Lieutenant-Colonel Greg Mirabella. Howard attended the Wangaratta wedding. But during Mervyn's family visit at Christmas 2006, he was given cause to worry. Colin told Mervyn he had given his former girlfriend a sum of money large enough that he had to cash in one of his pensions. The money, he said, was to help her buy a house because she and Greg could not afford it alone. Mervyn suspects, but does not know, that it was about $100,000. Further worrying Mervyn was his father's comment that Mirabella had asked him not to tell anyone about it.

Property records show that in March, just weeks after this conversation, Mirabella bought a house in Wangaratta for $695,000. That purchase is recorded in her parliamentary register of members' interests but no gift is recorded. (Gifts from friends are not required to be recorded if there is no appearance of a conflict of interest.)

After Mervyn had returned to Britain, he quizzed Mirabella about money. In a measured email sent on January 6, 2007, he asked: ''Do you and your husband think it is appropriate to be accepting a gift like this from Colin?'' Mirabella's response was furious: ''I do not expect that you ever did or ever will understand Colin's relationship with me.''

Lesley and Mervyn were to find out later that, around this time, their father had transferred his full power of medical and financial attorney to Sophie Mirabella. His married ex-girlfriend, the executor and possible beneficiary of his will, was now to also have sole power over his affairs as he aged.

On March 13, 2007, Colin sent a typed letter above his signature, now grown quite childlike, stopping all contact with Mervyn.

''Any further such correspondence to Sophie or me will be ignored. I wish never to hear from you again.''

Mervyn was devastated. ''The venom in his letter really got to me,'' he told the Herald. ''It was a devastating thing to read.''

Letters over the decade leading up to this point, which the Herald has seen, show how out of character this correspondence was. They were loving and intimate.

A series of emails followed Howard's letter, during which Mervyn and Lesley tried to extract details from the Mirabellas about their father's financial status and health. Most, they claim, were either ignored, rebuffed or answered curtly. But during 2007, it became clear that Colin was not in Melbourne for long stretches. Lesley could not find him. She tried, without success, to contact the Mirabellas.

''But short of going to Wangaratta and walking around with a placard saying 'have you seen this man', what could I do?''

This was impossible because in November of that year, Lesley herself had an accident which stopped her travelling. When she finally did see her father on a trip to Melbourne, he would only say he was staying ''with friends''.

In September 2008, though, Mirabella called her. Colin had had a fall. He was in intensive care in Wangaratta Base Hospital and may not survive the day, she said. Lesley drove up and discovered her father in a coma, concussed, feverish, suffering from a urinary tract infection, a collapsed lower lung and a lung condition.

Lesley discovered that Howard had been living in a farmhouse on the Mirabellas' property, about 400 metres from the main house. He was unable to wash himself and was incontinent.

Howard recovered from the acute illness but while in hospital was diagnosed with Alzheimer's disease and was placed in a nursing home.

In November, Mervyn came from Britain. He had neither seen nor heard from his father since the email of the previous year. But Howard was delighted to see him.

''At first he looked at both of us and said, 'I know I didn't want to see you again but I don't remember why,' '' Mervyn told the Herald. ''It was very emotional.''

On September 2 this year, Colin Howard, QC, died, aged 83.

But for his family, the manner of his becoming ill and the way he became isolated from everyone but the Mirabellas remains cause for serious questions.

In April last year, Mirabella engaged lawyers. She told the family Howard's financial details and his will were private matters.

''We are very upset with Sophie Mirabella,'' Mervyn Howard said. ''We believe she adopted a deliberate tactic to split our family. And it happened immediately after my father told me that he had made a financial contribution to her by cashing in a super entitlement to help them buy their house in Wangaratta … we did not get to see him; we missed a chunk of the last five years of his life.''

Mervyn and Lesley Howard insist they are not after their father's money. He made it clear to them that they should expect none.

It's clear to the siblings that their father's feelings for Mirabella did not waver, before or after her marriage. But they will not give up. What they want is to know that Mirabella - parliamentary pugilist and Tony Abbott's spokeswoman for innovation, industry and science - did the right thing.