When her grandchildren were born, Helen says her mother was dismissive and uninterested. She denounced Blossom, at one, as ‘a little madam’, Bailey as a ‘bad-mannered boy’. Today, Helen believes that Elinor resented her grandchildren because they were a rival distraction from her own imagined needs, but at the time, she says, ‘I was gutted.’

Alan died of emphysema and heart failure in 2008, and things came to a head two years later when Elinor announced that she had Parkinson’s disease. ‘It was Christmas, I was pregnant with Bailey and those things seem to have been a trigger, prompting her to take her illness to the next level.’

The three main symptoms of Parkinson’s disease, a condition affecting one in 500 people, in which parts of the brain become progressively damaged, are a tremor, slowness of movement and stiff muscles.

Again, Elinor had chosen a disease for which there are no conclusive tests. She was diagnosed with ‘mild Parkinsonism’ and the consultant said that she should have at least 10 years of normal life ahead of her. Yet her demands for tests and consultations escalated and, whenever they came back negative, Helen says that she was affronted.

So how exactly did she fool medical professionals? Helen believes her mother was able to string them along for so long, and receive a formal diagnosis, because she produced symptoms – a hand tremor, stiffness and a shuffling walk. ‘Doctors and nurses don’t expect people to lie to them. And because of patient confidentiality, they don’t get the full picture from family and friends. That’s not what they’re interested in; they treat the symptoms as presented.’

It is impossible to know the extent to which Elinor faked the symptoms – and indeed whether any were genuine – but one comment is telling: ‘When the doctor told me I had ME, that was it – no further treatment, no doctors involved, off you go and work it out for yourself. But with Parkinson’s I get nurses and consultants and there’s so many different drugs and treatments.’

For four years, Elinor had a regular Parkinson’s nurse appointed by the NHS to monitor and support her. ‘Whenever I phoned my mother, I could tell if she had spoken to the nurse because she’d sound so euphoric. It was weird.’

The new medical condition put even more demands on Helen as she shuttled back and forth to help her mum or spent hours on the phone disentangling her complaints. ‘The bombardment was crushing me,’ she says. ‘It was a real strain between me and Peter to begin with, but once we realised she was putting it on, it brought us together in dealing with it.’

And yet Helen continued to stand by her mother. ‘I felt I couldn’t walk away,’ she says. ‘I was her only child. There was no one else for her.’

Then, in 2014, Elinor moved to a warden-assisted retirement complex in the Midlands, 70 miles away from Helen’s home in Nottingham – and each time there was an emergency, Helen duly drove there. ‘She started having falls, as many as 100 a month. It was ridiculous by the end.’

The most traumatic encounter came in January 2015 when Helen visited her mother alone in her flat. By then, Helen says, the Parkinson’s nurse had also commented to her that Elinor’s symptoms were suspicious. ‘[The nurse] was very firm with me,’ Elinor told her daughter. ‘Said I had to stop making up illnesses and faking falls and enjoy my life… It’s been flagged on my notes that I’m not to be admitted to hospital for a fall.’ Helen comments in the book: ‘She said it so matter-of-factly, as if she didn’t understand that she was being called a liar and a time-waster.’

Helen arrived to find her mother demanding to be lifted into bed. When she said she couldn’t do this, Elinor staged a controlled fall. As Helen tried to take her arm to lift her up, she began crawling across the carpet, shouting, ‘You little bitch! Look at what you’ve done to me. You’re trying to destroy me.’

‘She was wild,’ says Helen. ‘It was terrifying. I decided then that I was never going back. I couldn’t risk this happening in front of the children. When you have children, you don’t take it any more, do you?’ She didn’t see her mother for the final two years of her life.

In 2015, a consultant psychiatrist was appointed to Elinor. He concluded in his assessment: ‘Mrs Page’s situation is one where the physical and the psychiatric cannot be easily unravelled and I am certain it is best not to try.’ Finally, in July 2016, her consultant neurologist reported: ‘She does not have straightforward Parkinsonism and does not respond to the treatment for this.’

Though Helen long suspected her mother had Munchausen’s syndrome, having read and researched it, she was never formally assessed and diagnosed. ‘It’s easy to spot in the diaries,’ she argues. ‘Her obsession with illness is there from the start.’ She never tried to get experts to confirm this theory as she believed Elinor would never agree to be investigated.

Elinor died of an infection while in a nursing home. The death certificate records the cause of death as Parkinson’s disease. ‘So she got what she wanted,’ says Helen.

‘Her death was a shock in a way my father’s death wasn’t and I fell apart. I’d lost the mum I’d wanted her to be. It was a huge grief. Peter was amazing. He really held things together.’

Helen retains a handful of fond memories of her mother – bedside conversations about clothes and the people they knew and school. ‘I thought we were close, but everything is tainted by what she did. Why was she lying in bed? Why was she not an active part of my life?’

Today, Helen says she is determined to be the best possible mother. ‘I want [my children] both to feel loved and adored and to feel a strong family bond. My parents wouldn’t have cared if I never handed in a piece of homework whereas I’m the complete opposite – my poor kids!’

She wrote her memoir in order to give it to them one day. ‘I worried that they’d get to 15 and ask: “So what happened with Granny?” I wanted them to have the full picture.’

Since her mother’s death, she has been reunited with an aunt, who she hadn’t seen since she was 14: Elinor had called her a dangerous bully. ‘I was nervous that she might be everything my mother had said. It was a relief to find she was the same as I remembered her – gregarious, fun-loving and adventurous. I hope for a lasting relationship.’

Helen still battles anxiety and self-loathing; she is currently having a form of therapy called eye movement desensitisation reprocessing (EMDR) to help with post-traumatic stress. ‘It’s amazing. I’m quite evangelical about it. After years of talking therapy, which didn’t really help, I feel like I’ve been set free.’

I ask if writing the book was cathartic too, but it wasn’t entirely. ‘It’s not like I’ve got it out and now I’m OK and can get on with my life. I can’t just leave it behind.’

Given that Elinor was in fact ill – struggling with a psychological disorder – I ask Helen whether this makes it easier to forgive her? ‘I don’t think so,’ she says swiftly. ‘I feel like it gives her an excuse and I don’t want her to have an excuse. She knew what she was doing. I want her to have responsibility for what she did.

‘You expect love to turn into hate,’ she continues with the resigned air of someone who has lived with sadness all too long. ‘But it’s not like that. I feel numb because I don’t really know who she was. I still find it quite hard to be angry at her. I would love her to have been a joy in my life and a loving granny. She could have had such a great life.’

*All family names have been changed

Extract: ‘I told her, “I used to pray every night that you’d get better”’ 

‘I saw the Parkinson’s nurse on Monday, and she was wonderful,’ Mum said, the light catching her face. We were walking through the park, I was heavily pregnant. ‘They’ve put me on a different medication, a stronger one,’ she continued.

‘It’s so different. When the doctor told me I had ME, that was it – no further treatment, no doctors involved, off you go and work it out for yourself. But with the Parkinson’s I get nurses and consultants and there’s so many different drugs and treatments.’

‘You don’t really mention the ME any more,’ I said.

She hadn’t had a rest that day so her ash-coloured perm was in perfect curls, bobbing around her ears as she walked. ‘I still have it.’

‘But you do seem much better.’

‘Hmm.’

I took an extra step and turned back to her so I could see her face. ‘This is the furthest I’ve ever walked with you,’ I said. ‘It’ll be a mile by the time we’re home. A few years ago, you couldn’t even walk to the corner shop. Don’t you think that’s amazing?’

She turned away from me as if something had grabbed her attention, but the grassy hill was empty. ‘I suppose.’

I laughed and shook my head.

‘I think it’s amazing. All those years the ME dominated our lives. All the things you couldn’t do – we couldn’t do. And now you can walk all this way.’

‘Look at those dogs over there,’ she said, pointing into the distance.

‘I used to pray every night that you’d get better,’ I said, refusing to be deterred.

‘So did I!’ she said, snapping round.

I breathed out a weak laugh. ‘I’m surprised you’re not happier then?’

She stopped and turned to me, her face shaded in darkness, her back to the dogs. She’d never liked dogs. ‘I am happy. But I’m not better. I have three chronic diseases now – ME, Parkinson’s and dystonia.’

‘That’s not what the doctors have said.’

She turned on her heels and strode away, her pace too fast for me and my ballooned belly. She whisked past the playground, taking the hill in large, fast strides as she discarded words in her wake.

‘I’ve been building up to telling you this. You’re not going to take it well, I just know.’

I hated it when she spoke to me like this, as if I were an unexploded bomb waiting to go off and she was the innocent victim tiptoeing over eggshells. I was panting to catch her, her voice trailing in the wind. ‘I’m getting worse and worse… I am trying, Helen. But I’m so ill. No one seems to realise how ill I am.’

Abridged extract from My Mother, Munchausen’s and Me, by Helen Naylor, is out on Thursday (Thread Books, £7.99)