WHEN ALISON WHITE climbed onto the plastic bath in her Glasgow home pointing her camera straight down at her two-year-old son, Louis, lying flat in shallow water, she had no idea that the photograph would become an iconic image of her severely mentally and physically disabled child.

That haunting image – showing Louis’s blond hair standing up around his gaunt, oval face, eyes wide spaced and blue – captures his “alien look,” writes White in her superbly written memoir, Letter to Louis. Now, it adorns the dust-jacket of her unflinching, unsentimental, life-enhancing book, which should be required reading for politicians, health workers and all of us who should care for carers everywhere – indeed, for anyone who has a heart.

As 52-year-old White writes, people who come into their lives are always drawn to that picture and exclaim, “I love this photograph. Wow, it’s Louis? He looks like an alien.” Actually, Louis, who is now a 21-year-old college student obsessed with his mobile phone, maps and music, looks like a mischievous, aquatic sprite, reminiscent of a favourite childhood book, The Water Babies.

“Do you know, you are not the first person to say that,” says White, who lives with husband, Greg, and their two younger children, Natasha (19) and Jack (16), in a remote corner of Pembrokeshire, in south-west Wales. They moved there from Glasgow to build a house to meet the then six-year-old Louis’s needs but near enough to a special school for him. The Whites also wanted a family home in a sequestered spot that would give Louis’s siblings the freedom to play and run wild.

They have since moved along the coastline, a bit closer to life and a village. “We’re still pretty difficult to get to, however,” laughs White, who grew up in Sheffield and studied in Leeds before setting up a successful landscape architecture business in Glasgow. She was also an artist, exhibiting her work in several Scottish galleries. Astonishingly, although she has always been a passionate reader, Letter to Louis is her first sustained piece of writing. A world away from the misery memoir genre, it’s a heroic book about hope – “hope in others, hope in systems, and hope for the future.”

“The last thing I wanted to write was a misery memoir. I was fearful and worried that people might categorise it that way because it’s about disability but it is actually about a mother’s love for her son,” she says, adding that she began writing it after doing a one-year Open University course in creative writing. How on earth did she find the time? “I literally just logged in at the most obscure times, mainly during the night – that’s the amazing thing about the OU, that you can do it all online.”

Repeating the words with which she closes her courageous story, she explains that she wanted to find a way to offer a glimpse into their lives, especially their daily life, to tell the story of a mother’s unconditional love for her son, whose suffering has often been unbearable, in order to give others a greater understanding of disability and caring. She also wanted to make people consider becoming Louis’s friend, or a friend to some other mentally and physically disabled person.

“It’s worth it, it’s a challenge, but it definitely makes you feel like you are alive,” she concludes. There have been moments of joy – as we shall see. But of course, she acknowledges, it has been hard, often heartbreaking and utterly exhausting.

There have even, as White freely admits, been times when, in the depths of despair and with Louis in constant pain and distress, she dreamt about ending it all, jumping off a cliff, holding him tight in her arms. There was, she confesses, a longing for escape – she even offered to leave her husband and their then small daughter so that they could lead a normal family life.

Louis’s story begins with his premature birth in a Glasgow hospital – which White chooses not to name – and chronicles his time in intensive care where his life hung by a thread. The story switches back to her pregnancy and the crucial moment when a midwife failed to check White’s blood pressure, resulting in pre-eclampsia, which can prove fatal for mother and child. Louis was finally allowed home 99 days after his birth. He was diagnosed with cerebral palsy when he was two-years-old – and is still a wheelchair user, although he can sometimes use a walker.

“Obviously I still think a lot about that midwife’s failure to check my blood pressure. Many, many times I think, ‘What if...’ and, ‘If only I had known.’ Things could have been so different. I honestly thought that midwife was protecting me,” says White.

The book is full of stories, such as the excitement when Louis speaks his first word – “Today” – and first walks a little – “Daddy, f****** hell!” he exclaims. But then there are the countless sleepless, bone-weary nights when Louis’s fragile sleep is constantly broken as he screams with pain.

Later, there is the stupid shoe shop assistant– Clarks – who refuses to sell Louis, who is in his wheelchair, a pair of shoes because he can’t walk across the room so that she can check the fit. There’s the occupational therapist who insists that Louis has to learn to wipe his own bottom – a physical impossibility – and who notes that White is babying her son. When Louis reaches 18, overnight respite care is suddenly withdrawn.

At one stage, they see five different social workers in eight months. But there are caring doctors and nurses, too. And there is the kindness of strangers: Louis wants to travel on the Tube in London – he requests an escalator for Christmas – and Transport for London staff radio ahead to ensure there is always someone to help the family at each station Louis visits.

White stresses that Louis has brought love and laughter into their lives – his discovery of the inappropriate use of the f-word, his mysterious antipathy towards comedian Phil Kay and his delight in telling everyone he meets that he has put his mum and dad’s pin numbers on Facebook. There are many such laugh-out-loud stories in the book. “Oh, I am so pleased you found some of it funny,” says White. “I don’t want people to think it is going to be a miserable read.”

Nonetheless, what was it like to relive so many terrifying memories?

“It was incredibly intense and emotional,” she replies. “I suppose it had been building up. More and more stories about our journey were inside of me. Louis was about to turn 18 and I thought, ‘If I don’t write this down now, I never will.’ Like you say, it was difficult, harrowing at times to go back to certain things that happened. Then, because I had done this one-year OU course, I had explored in a tiny way the story of me and Louis. I experimented and realised that I should write it to Louis.

“Although I knew that, I didn’t do anything about it. The trigger was unusual – I saw a memoir competition for Mslexia [“the magazine for women who write”]. Usually, they have novel competitions. I saw the ad three weeks before the closing date. It said, ‘Don’t enter unless you have a full manuscript.’ Of course I didn’t! But I just sat down and it poured out. It came out in a torrent – flashes of memory. A line would come to me and it would all burst out!”

White has gone to great pains to preserve the privacy of her husband – “Greg says he doesn’t need to [read the book]; he’s lived it” – and her other two children, but it is obvious that Louis’s disability has put enormous strain on their strong marriage and their loving family life. She’s immensely proud of Natasha, who is currently travelling in New Zealand, and Jack. They are both “happy and content, open and kind and caring.”

The family has, however, been to hell and back, but White says she regards her son as a gift. “It’s a funny word because people do sentimentalise it. Of course, I see Louis as a gift – he’s funny and amazing and he has taught me so much. He’s enriched all our lives – he enriches everyone he comes into contact with. He has an incredible personality. But I struggle with the fact that his disability has caused him a lot of pain and distress. I would not wish that on anyone, let alone a child.

“Now, I realise there are so many people in a similar situation but they can’t speak for themselves because you are so busy just getting by. I’ve reached a point where things are more settled, and I hope others will begin to understand and share our story. I want other carers to know they are not alone.

“Of course, the future is still frightening. I worry about Louis and his needs all the time, but I feel so much better now that I have written my letter to him.”

Letter to Louis, by Alison White (Faber & Faber, £12.99).