“My ability to function on the most basic levels was impaired massively because of the shock, pain and grief,” says Stephen Kinnaird softly, reflecting on the numb and chaotic few weeks which changed his life for ever. A busy businessman, he was devoted to his family but forced by his London-based job to be regularly apart from his family in Glasgow.

Now, following his partner Justine's sudden death at 46, he has found himself both "mum and dad" to Thea, 11, and six-year-old Elsa. He admits he struggled as he wrestled with his grief.

Justine Hird died in hospital on December 10 last year, four days after suffering a major stroke at the family’s home in Pollokshields on the south side of Glasgow. The stroke came without warning.

Stephen had just switched on his mobile phone after arriving at Glasgow Airport from a work trip when he learned that something was seriously wrong. “There was this barrage of messages and one said: 'I don’t know what’s wrong with Mummy.'”

In the taxi home, the driver’s conversation barely registered. Stephen paid the fare, ran inside and found his wife lying on the couch, clutching her arm, her eldest, panic-stricken daughter beside her. Justine's face, Stephen recalls, was drooping slightly on one side.

“She was smiling. I think she knew something drastic had happened to her body and was glad I was there to look after the girls.”

Tests soon confirmed Stephen's suspicions. Justine had suffered a major stroke, which happens when the blood supply to part of the brain is cut off. Her only symptom had been a slight headache earlier that day, which had been helped by a pilates class.

“The next day I listened to a voicemail from Thea and she sounded utterly panicked,” recalls Stephen, who is 48. “They had come back from a walk in Pollok Park and Justine had gone for a lie down and asked Thea to put her younger sister to bed, which was unheard of.

“About 10 minutes later, Justine had got up, walked through to Thea’s room and just went completely to one side. She managed to get to the couch and literally collapsed. She couldn’t speak and it was as if she couldn’t hear Thea. That’s when Thea knew there was something wrong. She had tried to get hold of me and when she couldn’t, she called an ambulance.”

The paramedics started going through the FAST test, the mnemonic used to help detect if someone has suffered a stroke: facial drooping, arm weakness, speech difficulties and time to call an ambulance.

“She couldn’t speak but was making groaning sounds. She was holding her arm and trying to move it.”

Justine was taken to Glasgow’s Queen Elizabeth University Hospital, while Stephen arranged for his mother to come and look after the girls.

“We were taken into a room and I knew straight away it was catastrophic because of the face of the woman who came out to speak to me,” he says. “One of the doctors cried when she saw I had two little girls.”

Justine underwent emergency surgery to try to ease the swelling in her brain caused by the stroke. Initially, the operation appeared to be successful. However, the day after the procedure Stephen was told the swelling on one side of Justine’s brain had spread to the other side and the doctors said there was no real hope.

“From then on in, you just go into a strange sensation,” he says. “I didn’t want to lie to the girls. Their aunt was helping them get the Christmas tree up. I got home and the girls were like, ‘Dad, look.’ It was heart-wrenching and horrible.

"I didn’t know what language to use to a 10-year-old, let alone a six-year-old. I sat at the kitchen table and googled ‘how to tell children their mother has died’ and stumbled on a page by the charity Barnardo’s which suggested using words like 'death' and 'dead' rather than 'gone for a long sleep' or 'to a better place', which will cause confusion.

“Young children need to be told repeatedly that when someone dies they can never come back.

“I spoke to people who had lost parents young because I didn’t want to make bad choices and one of the big things that came across after speaking to people who had lost a parent at a young age was that things had been brushed under the carpet. They weren’t allowed to go to the funeral.

"One woman told me she had grieved for the loss of her mum when she gave birth and I just thought, 'I don’t want that to happen.'

“I was really focused on keeping Justine’s memory alive. The girls must know it’s OK not to be OK and that they are allowed to cry. I see families through bereavement counselling I go to and there are afraid to show their emotions and hide it from their children. I was keen to make sure they were at the funeral, but if they wanted to bail, they could do that.

“We had a lovely celebration of Justine’s life at Pollokshields Burgh Hall. I was hovering above it all, but it felt like a wedding. There were lots of children running around.

“For the first two weeks after Justine passed away, Thea got angry and upset even at the word 'mummy'. She asked me to refer to Justine’s phone as an iPhone not 'Mummy’s phone'.

“I made a huge effort to try to keep everything the same, such as after-school club and bedtimes. The thing that’s really important is keeping discipline the same. And it’s hard at times because they are pushing boundaries. They are upset and sometimes they even use it as an excuse to get their own way, so you have to recognise that.”

Stephen says he drew enormous strength from the community, including parents, neighbours and teachers at his daughters’ primary school who rallied to offer practical and emotional support.

“I stood up at the funeral and spoke to everyone. I said, 'I’ll need everyone’s help because I will go down at some point,' and I asked for the girls' help, spelling out to them that I’m now doing the job of two people.

“One of the clear things that happened was how my local community came together to give me support, both practically and emotionally.

“The day after Justine died, the head-teacher said, ‘This will feel wrong but get the kids back in tomorrow, they will want to be normal. If you keep them off, they will just mope around and they will feel your pain.' So they went back to school the next day and it was the best bit of advice ever because they immediately responded.

“My ability to function on the most basic levels was impaired massively because of the shock, pain and grief that came from losing Justine. I suffered short-term memory loss for the first three months.

“I kept losing keys, phones and forgetting dental appointments. Justine was amazing as a mum. She made it look effortless. Now, on the other side, I am having to learn those skills."

Former footballer Rio Ferdinand opened up about life as a widowed father after the loss of his wife Rebecca to cancer in 2015, at the age of 34, for an intensely moving BBC documentary.

The ex-Manchester United player said juggling the demands of single parenthood meant he “hadn’t given himself the space to grieve”. Stephen went through a similar experience.

“In the first months of really struggling with grief and anxiety I never took time for myself and concentrated on the girls," says Stephen. "This resulted in throat infections and being very run down for a long period. On seeing the girls doing so well, I am now slowly adjusting to my new role as Mum and Dad and I am making sure I take good care of myself.”

Both Steven and his daughters were helped by the Butterfly Service, run by the Prince and Princess of Wales Hospice in Glasgow, which offers counselling to children and young people who have suffered the loss of a parent, and respite for carers.

“Something that has surprised me is how resilient children are. They have an ability to dip in and out of grief, one minute being really upset and then the next away playing and appearing to be having fun and happy.

“They are doing exceptionally well. I think Thea is finding it harder because Elsa was at an age where she is going to bounce back. Because we had such a healthy approach to memories, she is thriving. Thea tends to bottle things up, then she gets angry. I’m bracing myself for puberty and trying to stay calm.”

Stephen, who now works from home, set up a JustGiving page within a week to provide a positive focus for the family, raising more than £6,000 in the run-up to Christmas for the Stroke Association. Some of the messages he received from strangers were profound, he says. Tomorrow he will run the Great Scottish Run half marathon to boost the total further. He’s also planning to write a book to help other bereaved parents.

“I feel that I have learned a great deal that could help other parents finding themselves in a similar position. Justine was really warm, really considerate, really caring towards people. She taught me a lot about just being a bit less selfless. I want to continue that for her.”

Visit princeandprincessofwaleshospice.org.uk/hospice-care/our-services/butterfly-service. To donate to Stephen Kinnaird's fundraising campaign visit justgiving.com/fundraising/stephen-kinnairdforjustine