A little boy suffering from leukaemia whose widower father was able to take a year off work to care for him thanks to colleagues’ generosity has returned to nursery school after being declared well enough to leave hospital.

Julius Graf celebrated his fifth birthday by going home after weeks of life-saving chemotherapy.

His father, Andreas, says he will forever be grateful to work colleagues who donated more than 3,000 hours of overtime so that he could stay off work to care for Julius just after the boy's mother died.

Julius was just three years old when he was diagnosed with leukaemia early last year, and Mr Graf, 36, used all his annual leave from the design company where he worked to be at his son’s hospital bedside.

But when the boy was well enough to return to the family's home in Fronhausen, in Hessen, Germany, his mother suddenly died of heart disease.

With no holiday allowance left, Mr Graf was worried he would lose his job as an assembly worker, and was struggling to cope with both his son's illness and his wife’s death.

But Pia Meier, the company’s human resources manager, appealed to the factory's workers to donate their overtime - and all 650 signed up, even those who had never met Mr Graf.

Within two weeks, at an average of five hours for each employee, they had raised 3,264.5 hours, which the company allowed him to take as paid leave.

The total was equal to 81.6 weeks - or more than 18 months.

“Without this tremendous help, I would've been out of a job by now,” Mr Graf said, adding that he would be eternally grateful to his colleagues and the company.

Recalling when he was first told about colleagues’ generosity he said: “At first I was speechless, could not say anything. I cried in front of friends and was completely overwhelmed.”

He has cooperated with media publicity about his case out of gratitude to colleagues, he said.

Andreas Graf: 'At first I was speechless' (RTL Hessen)

And he has since also been touched by offers from strangers to donate towards Julius’s care.

“Recently, an 89-year-old wanted to donate 20 euros. But we did not have the heart to accept that. That's overwhelming,” he said.

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His son will still have therapy until August, he said. “He gets syringes every four weeks and also low-dose chemo-tablets. But Julius copes very well. We are on the right track, but that does not protect us from relapse. He must be cancer-free for five years to be cured.” He goes to nursery more now, depending on how he is feeling, his father said.

Ms Meier said she had also been overwhelmed by the response from staff, pointing out that not a single worker declined to donate.