Sara Keays, her daughter Flora and I were sitting in their kitchen eating sandwiches. Their Gloucestershire home, a 1704 Grade I listed building with rococo plasterwork, was, despite the Aga, almost as cold inside as it was freezing outside.

It was a grey December day in 2008. Around our sandwiches was a carefully arranged selection of rather ancient-looking autumn leaves — though the reason for their presence would not become clear until later. Flora, then 25 and 5ft 10in, bore an astonishing resemblance to her father Cecil Parkinson, who died from cancer earlier this week at the age of 84.

She was desperately ill as a child and had also been diagnosed with Asperger’s syndrome — a form of autism that makes it difficult for sufferers to form relationships.

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Celebration: Sara Keays and her daughter pose for Flora's 18th in 2002, but there was no card from Parkinson

Despite that, when I had arrived, Flora had been polite and welcoming. In many ways, she is a vivacious character and, over the years, had enjoyed gymnastics, ballet, ice-skating and horse-riding. She had also learned to drive.

I knew from past meetings that Flora loved to paint her nails, so I had bought her some nail polish. She thanked me politely, then struggled to remove the thick plastic packaging. ‘Goodness me, this is harder than a workout at the gym,’ she laughed.

Sara laughed proudly at her daughter and her face, stiff with stress, relaxed for a moment.

‘Flora has a really good brain, it’s just that it’s a brain with things missing,’ she said.

While the many obituaries this week for the Tory grandee touched on his political skill, charismatic chairmanship of the party during the 1983 election victory and steady hand as a Cabinet minister, few came close to conveying the anguish of the secretary with whom he had a 12-year affair — but whom he abandoned to raise their daughter alone after news of the scandal broke in the months after that General Election.

When Parkinson learned she was pregnant, he callously made it clear she must have an abortion.

When she refused to agree to this, he said he would have absolutely nothing to do with the child.

The first time I met Sara, in 1997, I wrote that at times she reminded me of a trapped animal: determined still to fight her corner, but with nowhere left to go.

I have interviewed Sara several times since that first meeting, including when Flora was 18, when they marked the end of a draconian injunction that Parkinson had secured to stop any mention of his daughter during her childhood.

Newborn: Sara leaving hospital with Flora in 1984

We spent several days together, during which time I felt I got to know Sara well. At first, she had a defiant, jolly hockey sticks air. But it was, I soon learned, a show put on for my benefit.

The elegantly bred colonel’s daughter told me: ‘It’s not exactly stiff upper lip and all that, but it is not in one’s nature or upbringing to sound like a big long moan.’

Once a beautiful, clever, successful career woman, Sara seemed racked with bitterness and frustration. And who could blame her?

Her affair with the oh-so-suave MP, 16 years her senior, was not a casual fling. Sara believed Parkinson when he said he wanted to marry her, even though he had long been wed to Ann, a wealthy builder’s daughter, and had three daughters.

Some said that Sara had deliberately got pregnant to put pressure on him to leave his wife, but she always denied it.

‘It didn’t occur to me when I started feeling unwell that I had morning sickness,’ she told me.

‘When I found I was expecting a baby, I was surprised, excited and nervous. Of course, the circumstances were most unfortunate, but I really loved the father and believed that he loved me.’

I suggested to Sara in the gentlest terms that perhaps she shouldn’t have got involved with a married man — especially one who thought he was irresistible to the ladies — nor believe the old story that he would leave his wife.

I remember she snapped at me so fiercely it made me jump.

I later believed that her response had been a knee-jerk reaction to a question that, despite the passing of time, touched an unhealed raw nerve.

Sara had been so profoundly wounded by the man she loved that over-reacting was her way of self-protection.

Suddenly snapping like that was also, perhaps, a result of spending so much time on her own with Flora. Though she admitted when I went to see her that she was pleased to have another adult to talk to, she was, to a certain extent, out of practice at conversing easily.

After Parkinson made it clear he would stay with his wife, he returned to the political limelight and later served briefly as William Hague’s party chairman.

Sara, however, had lost her lover, her job, her reputation and some friends. Apart from contact with her family — two brothers and three sisters, including an identical twin — she had a ‘totally isolated existence’, and she and Flora have lived in the shadows ever since.

Her most ardent and constant supporter was her father, Colonel Hastings Keays, who died aged 90 when Flora was 12. Sara’s mother Mary had died of cancer in 1980.

Sara told me about her father’s reaction when she told him she was carrying the baby of a married Cabinet minister: ‘My father was very broad-minded and, like me, appalled at the idea of an abortion.

‘He felt I should be protected by the man responsible, particularly after Parkinson [she never once called him Cecil] rang him and said: “You are speaking to your future son-in-law. I am not a rat.” ’ Little wonder, then, that the death of her father hit Sara so hard.

His passing was a profound loss and one Sara had dreaded, partly because he had developed such a warm relationship with Flora, who had become so tragically unwell.

Flora had been a bright, lively baby, but at 18 months began to have epileptic fits. By the age of three, she was having them almost continuously and virtually lost the power of speech.

Millionaire: Cecil Parkinson, who this week died of cancer at the age of 84, is pictured with his wife Ann in 1992

‘It was so incredibly worrying and distressing,’ said Sara. ‘She was continually banging her head on the hard surfaces around the house. I padded everything — arms of chairs, the bath, corners of tables.’

At four-and-a-half, Flora had a five-hour brain operation — a last resort to relieve the epilepsy.

But as a consequence, she lost part of her brain, including the right frontal lobe, which deals with reasoning and deduction.

It has left her with serious social and learning difficulties, and on top of that she was also diagnosed with Asperger’s syndrome.

For a while after the operation, she hovered at death’s door. Then began a slow recovery.

‘Flora hardly spoke for 18 months, but the epilepsy stopped,’ Sara told me. I asked her if she had ever thought it might be divine retribution given the circumstances of her conception.

‘I don’t believe in that sort of twaddle,’ she replied briskly. ‘And even if I did, it would be pretty unjust that my child would be punished.’

Flora’s level of brain damage and autism seemed to be such that she knows what she is missing in terms of leading a normal life, yet is powerless to do anything about it. Sara explained: ‘She longs for company, but has great difficulty in making relationships.

‘She has a totally literal understanding of language and of the world. If someone says they’re half-dead, she believes they are physically in that state.’

It makes Flora very vulnerable.

Since her daughter’s illness developed, all Sara’s obvious qualities have been channelled into the needs and demands of her daughter.

When I found I was expecting a baby, I was surprised, excited and nervous. Of course, the circumstances were most unfortunate, but I really loved the father and believed that he loved me Sara Keays

Her formidable character, and experience of the workings of Westminster, could have made her a fine MP — and she did try to put herself forward as a candidate after the affair emerged.

Realistically, though, she never stood a chance of being selected.

Instead, all her passion and commitment went into fighting for her daughter’s interests. And that included a battle for financial support from Cecil Parkinson.

Just two weeks before Flora was born, the pair had agreed child maintenance payments — but as the years passed, Sara felt Flora’s significant disabilities meant she needed more financial support.

In 1987, Sara’s lawyer approached Parkinson’s lawyers to agree a new financial deal.

‘I have always had to ask [for money],’ she said. ‘The whole thing was incredibly dragged out. We finally got to court just before Flora’s major brain operation in 1988.’

She accepted the new arrangements that were offered only because she was so drained from looking after Flora that she had no energy to fight for more.

But as the demands of Flora’s care steadily mounted, Sara took Parkinson to court again in 1992.

But this time he fought back. ‘If I hadn’t taken him to court once more, he wouldn’t have ended up getting the injunction imposed,’ she said. ‘But I had a very sick child and I needed more help.’

She also tried to boost her income by writing two books: A Question Of Judgment, in 1985, that chronicled her affair with Parkinson, followed by a novel, Black Book, in 1996 after the secret ‘black book’ that records MPs’ financial and sexual misdemeanours.

Parkinson secured his draconian injunction a year after he was elevated to the House of Lords in 1992. It meant no one — including Sara — could discuss Flora’s life in public or do anything that could lead to her identity being revealed.

So it was that, at her father’s behest, Flora effectively became a non-person. The injunction prevented even Flora herself from talking about her own life.

‘Do you know, the restrictions were so severe that when Flora participated in an ice show, the school couldn’t put her name in the programme? It was as if she didn’t exist,’ Sara said bitterly.

The restrictions lapsed, however, when Flora was 18. Only then could it be revealed that Cecil Parkinson — by then Lord Parkinson — had never seen his daughter nor even sent her a birthday or Christmas card. In stark contrast, the millionaire lavished love and money on his three daughters from his marriage to Ann, the wife he wouldn’t leave.

In 1983 Lord Parkinson masterminded Margaret Thatcher's election victory (the pair are pictured celebrating)

While at least one daughter was bought a horse and they all enjoyed expensive holidays, Flora and her mother were forced to scrape by.

Shortly after her grandfather died, Flora began to ask questions and wanted to know why her father was never in touch with her.

When we last met, seven years ago, Sara told me that Flora’s anxieties had also prompted her to ask: ‘What is going to happen to me when you die, Mummy? Will my father be kind to me? Will he help me?’

Sara said that she had replied in all honesty: ‘I don’t think so.’ Then, in her late teens, many of the autistic features of Flora’s childhood re-emerged.

‘Her repetitive behaviour became desperate and she couldn’t bear anything around the house to be changed. Those leaves,’ Sara said, pointing to the kitchen table, ‘have been there for three weeks. I didn’t want to risk moving them in case I upset her before you arrived.’

Suddenly Sara’s face whitened and she collapsed in tears.

The immense and unremitting responsibility of her daughter’s wellbeing weighed so heavily upon her. She left the room to compose herself and apologised when she returned.

‘I am so tired,’ she said, her voice faltering. ‘Flora has had to bear so much. At least I have had some experiences and happiness in my life that she will never know.’

Here was the real tragedy of the Cecil Parkinson scandal. If Flora had been entirely well, she and Sara could have forged a happy, mutually supportive family unit. Instead, Flora’s disabilities compounded Sara’s fall from grace and left her living a twilight life with little prospect of contentment.

For all that, as we continued to talk, there were flashes of another, more positive side to Sara — one that I imagined must have appealed so much to Cecil Parkinson.

She was quick-thinking and articulate, sometimes very funny, and had a contagious laugh that lit up her face.

Sadly, these bursts of liveliness did not last long. Flora hungrily devoured all her mother’s attention. But not once did Sara get irritable: instead, she would painstakingly explain things and calm her daughter if she became agitated.

We haven’t spoken for a while, but I remain very fond of Sara and Flora — who has just turned 32 — and profoundly moved by their predicament.

Of course, some people will say that any woman who had a long affair with her married boss must take a share of the blame for what came afterwards.

In that regard, it is illuminating to hear Sara’s view of how she could have so misjudged the man she once loved.

‘Love is blind and I think he was in love with me,’ she said eventually. ‘I am not the first woman who has made a misjudgment about a man.’