The pilot had been very patient but, after an hour of the plane waiting on the Tarmac at Heathrow, with my son Stephen refusing to get up off the floor, sit in his seat and buckle up, our bags were removed from the hold and he was carried off the flight, my husband Roy and I walking, hot-cheeked and humiliated, behind.

Our family holiday to Greece would not be going ahead, after all.

And no, Stephen was not an obstreperous toddler when this happened. He was 45 years old. This embarrassing scene happened two years ago and the episode is just one of the many challenges we have faced since Stephen, our second child, was born with Down's Syndrome.

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Worried about the future: Gillian, 69, with her son, Stephen, who has Down's Syndrome

So difficult has it been that I can honestly say I wish he hadn't been born.

I know this will shock many: this is my son, whom I've loved, nurtured and defended for nearly half a century, but if I could go back in time, I would abort him in an instant. I'm now 69 and Roy is 70, and we'll celebrate our golden wedding anniversary next month.

We were childhood sweethearts and married when I was just 19 and he was 20. I sailed through my first pregnancy with Andrew a year later, and both of us were really looking forward to a second baby to complete our family.

There were no antenatal scans or blood test to detect abnormalities in those days and although I had a sixth sense, call it mother's intuition, that there was something wrong with my baby, the doctors and midwives insisted I was being hysterical and refused to perform an amniocentesis (where cells are taken from the amniotic fluid and tested). A healthy 22-year-old, with a thriving baby, I was considered very low risk to have a Down's baby.

Stephen came into the world one Sunday in January 1967 at the Kent & Canterbury Hospital.

The following Wednesday, I looked at him in his cot: his small, almond-shaped eyes, broad, flat nose and the one crease on the palms of his hands.

Not what she planned: Gillian sailed through her first pregnancy with Andrew, left, and was looking forward to a second baby completing their family. She didn't know Stephen had Down's when she was pregnant

Delayed milestones: Stephen didn't walk until he was five

'He's a mongol, isn't he?' I gasped to my mother. It sounds shocking now but that was how we used to describe people with Down's Syndrome in those days.

She told me she was sure he wasn't, and it seemed everyone else was blind to what I saw so clearly. None of the doctors and health visitors even mentioned it, so for seven months I blundered on, trying to convince myself that my baby was 'normal'.

However, when Stephen became ill that summer and I took him to hospital, I overheard a paediatrician refer to him as a 'mongol baby'. I had been right all along.

In that instant, my world came crashing down around me.

I'd never had psychological problems before, but I believe that parenting a mentally disabled child could push anyone to the edge

Questions I couldn't answer raced through my mind: Had I caused his disability? How terrible would his life be? What impact would it have on his brother Andrew, then only two? How on earth would Roy and I cope?

That was the day normal life ended for Roy, Andrew and me.

Perhaps you'd expect me to say that, over time, I grew to accept my son's disability. That now, looking back on that day 47 years later, none of us could imagine life without him, and that I'm grateful I was never given the option to abort.

However, you'd be wrong. Because, while I do love my son, and am fiercely protective of him, I know our lives would have been happier and far less complicated if he had never been born. I do wish I'd had an abortion. I wish it every day.

If he had not been born, I'd have probably gone on to have another baby, we would have had a normal family life and Andrew would have the comfort, rather than the responsibility, of a sibling, after we're gone.

Stressed: Gillian believes the family would have been happier if she had aborted Stephen and gone on to have another baby

Gillian and Roy's marriage has lasted: But they've had a difficult time raising a mentally disabled child

Instead, Stephen - who struggles to speak and function in the modern world - has brought a great deal of stress and heartache into our lives.

That is why I want to speak in support of the 92 per cent of women who choose to abort their babies after discovering they have Down's Syndrome. Mothers like Suzanne Treussard who bravely told her story in the Daily Mail two weeks ago.

Suzanne, who was offered a termination at 15 weeks, braved a backlash of criticism and vitriol from some readers.

But I'd challenge any one of them to walk a mile in the shoes of mothers like me, saddled for life as I am, with a needy, difficult, exasperating child who will never grow up, before they judge us.

They should experience how it feels to parent a grown man, who is no more able to care for himself than a toddler - and at a time of life when your children should, all things being equal, be taking care of you.

They should know how it feels to live every single day under a crushing weight of guilt.

They should know how it feels to watch Stephen's constant suffering and witness the almost daily destruction wreaked on all our lives.

Roy, like a lot of men of his generation, is not terribly good at showing his emotions, and never says much about Stephen's condition.

He loves his son, but knows he cannot be 'fixed', so chooses not to waste time contemplating the 'what-ifs'. For my own part, however, I don't think I will ever come to terms with Stephen's disability.

In his early years, it caused me physical pain seeing friends' toddlers reaching milestones when my son was still so baby-like. Stephen didn't walk until he was five and couldn't speak - even now he has only a few words and communicates using Makaton, a form of sign language. This made working out his needs a constant struggle.

His incontinence meant that washing his clothes and bedding became my full-time job.

Needed support: As a child, Stephen stayed at a specialist hospital in Ramsgate, Kent, when his mother couldn't cope

I'd been a radar operator and intelligence clerk in the RAF before I was married. But now my life was taken up by trying to meet Stephen's needs - let alone those of Andrew and Roy.

So, exhausted and racked with guilt, I was close to the end of my tether when, shortly after Stephen's third birthday, he became unwell and cried incessantly for three days and nights.

Worse still, he could give me no indication of what was wrong with him.

My husband was working late shifts as a driver at the time, and by the third night I couldn't stand the noise any longer.

In a rage, I picked Stephen up with every intention of throwing him down our flight of stairs. Thankfully, by the time I reached the top step, I thought, 'What on earth am I doing?' and put him back into his cot.

A couple of days later I was admitted to a psychiatric hospital suffering a nervous breakdown.

I was prescribed tranquillisers and then treated as a day patient for several months afterwards.

He only seems happy when sitting alone in his room watching the same old DVDs of the Muppets, Worzel Gummidge and Benny Hill. And what life is that for a grown man?

I'd never had psychological problems before, but I believe that parenting a mentally disabled child could push anyone to the edge.

Recognising that I could no longer cope, our GP arranged a respite place for Stephen at a specialist hospital in Ramsgate, Kent.

I was consumed with guilt - I'm his mother and the nurses told me he cried a lot in the beginning, presumably because he missed me - but I knew I wasn't strong enough, physically or mentally, to care for him every day. When a permanent residential place for Stephen was offered at a nearby hospital, Roy, our GP and I decided this was for the best. I honestly felt nothing but relief that the problem had been resolved.

Years later, I was told by a professor studying the parents of children with disabilities that it is very rare for marriages to survive.

Although Roy and I have always had a solid marriage, we were both deeply unhappy. Our unhappiness followed us everywhere, like an unspoken frosty presence in the room.

Once Stephen moved to the hospital I saw him as often as I could, while still meeting the needs of the rest of my family.

It turned out the reason Stephen had cried so much over those three days was that he had a hereditary condition, unconnected to Down's, called haemolytic anaemia, which meant his red blood cells were being killed off quicker than his bone marrow could produce them, leaving him drained and exhausted.

Will never grow up: Stephen will always need constant care

One day, Stephen's doctor sat us down and told us that Stephen needed an operation to remove his spleen. Without it, he said, he would 'go to sleep and never wake up'. Those were his exact words.

Looking back, I believe the doctor was guiding us towards allowing our son to pass away naturally, but we were not much more than children ourselves, in our mid-20s, and didn't understand then what he was trying to do for us.

I wish we had - it would have spared us all a great deal of pain. Instead he had the operation and spent five weeks at Great Ormond Street Hospital recovering, with me at his bedside as often as possible.

Rising risks A 20-year-old mother has a one-in-1,500 chance of giving birth to a baby with Down's Syndrome, rising to one in 100 at the age of 40 Advertisement

His weekend visits home became harder to bear as he grew older.

I didn't drive, so would take him into Canterbury on the bus to do the shopping. However, more often than not, he would refuse to get off the bus and sit in the middle of the aisle where people would have to climb over him.

So we'd have to wait for the bus to turn around and go back past our house where I'd have to get Andrew to help me physically remove Stephen from the bus.

It made me very reluctant to leave the house, but even at home he would use sit-down protests as a way of refusing to go to bed, get dressed, get in the bath and even eat.

But then, when Stephen was 11, he came back to live with us full-time for 18 months.

They were the longest 18 months of our lives. I barely left the house because I couldn't take Stephen with me, nor did I dare risk leaving him home alone.

He was still incontinent, barely able to communicate, and getting bigger, which made moving him when he staged one of his sit-downs even more difficult.

Role reversal: Roy and Gillian are reaching an age where their son should be looking after them

Again my mental health began to suffer. So it came as a huge relief when, aged 13, a place came up for him at a boarding school for children with learning difficulties in Folkestone. Since leaving school he has lived in about five different local authority houses, visiting us every other weekend and for holidays.

He now lives in sheltered accommodation in Kent with two women who also have Down's, and where they have 24-hour support from carers.

When we go to pick him up at the weekends, we have no idea what will happen. Sometimes he refuses to come with us, sometimes he insists on being taken back to the home as soon as he's had a biscuit and a drink of water or, if we're lucky, he will be happy to stay.

He came home last Christmas Eve and we all went to a neighbour's party, which he enjoyed.

The following morning he opened his presents and then insisted I take him home immediately.

When we take Stephen shopping, or to restaurants, he stages sit-down strikes, just as he did on the aeroplane, and will refuse to move for up to three hours.

Only a parent of disabled children can truly understand those fears that will haunt you beyond the grave

He only seems happy when sitting alone in his room watching the same old DVDs of the Muppets, Worzel Gummidge and Benny Hill. And what life is that for a grown man?

Don't misunderstand me, we have had some lovely times with Stephen. Like when we took him to Disney World in Florida ten years ago.

He loved the rides - his favourite was Dumbo the Flying Elephant - although poor Roy had to accompany him on every single one.

At times like these he's brought a magical, childlike quality to our lives, but I'd trade every single one in a heartbeat for the joy of seeing him settled with a wife and children, or established in a career.

I'm sure I will mourn missing out on seeing him achieve these milestones until the day I die.

And that brings me to my other big worry. I feel pretty sure now that Stephen will outlive his father and me and I do not know how he will cope after we're gone.

He just won't have the mental capability to understand why we're not turning up to collect him any more. And, once we're gone, who will keep him safe?

When he lived in his first local authority home after leaving boarding school aged 18, we'd notice bruises on his arms when he visited at the weekends.

We were convinced he was being physically abused - he said that one of his carers had pushed him into a swimming pool - and we fought very hard to get him moved out of that home.

Only a parent of disabled children can truly understand those fears that will haunt you beyond the grave.

Of course, although we've never said it out loud, I think Andrew is very much aware he will be ultimately responsible for Stephen.

Something like that is never voiced, it's just an automatic responsibility.

And I feel terribly guilty about that.

He lives hundreds of miles away in Cornwall and is about to become a father for the first time, aged 49.

His partner is 38 and, thankfully, they were at no greater risk than anyone else of having a Down's baby.

TELL US WHAT YOU THINK Was Gillian right to keep her Down's baby? We want your personal views and stories. Email: dm.femail@dailymail.co.uk Advertisement

Years ago, I was so worried about history repeating itself that Andrew, Roy and I went for genetic counselling at Guy's Hospital in London and found Stephen was just 'bad luck'.

I say 'bad luck', but that's the greatest understatement that anyone can imagine.

And so I appeal to every mother-to-be out there, facing the knowledge that they may bring a child like Stephen into this world. Read my story and do what is right for you and your family.