Justin Yerbury is a world leader in motor neurone disease (MND) research . Two years ago, he began to develop symptoms of the disease himself and by the end of last year his condition was critical. Using eye-gaze technology to type, he describes here the encounter that inspired him to undergo drastic medical intervention.

As we stood on the doorstep waiting for someone to answer the bell, I wondered what he would be like. I wondered what we would talk about, or what I should ask him. My girls and I were a bundle of nerves and I was pinching myself to make sure this was really happening.

We had been cautioned that the reality of meeting Stephen Hawking was far from his polished appearances on TV and that his current condition could be confronting. Despite the warnings and the awkward initial introductions, he was engaging and genuinely interested in the conversations we were having, seated around his dining table.

He gave me a rundown of the milestones of his motor neurone disease, from his diagnosis to using a wheelchair and then the tracheostomy. He was very engaged and very witty. I explained to him how hard it was to tell people how bad motor neurone disease is when he had lived with it for more than 50 years. He appreciated the irony.

Stephen was diagnosed with MND in his 20s, so each step had been a slow adjustment for him. But MND usually takes hold in a matter of years, not decades, as it has in my experience. I was inspired by Stephen's attitude and cheekiness after living with this insidious disease for so long.

At the meeting, I felt that I was in a decent condition, although my right arm was totally paralysed and my left had lost significant strength.

My condition worsened rapidly after that trip to Cambridge and by the end of last year I was unable to walk and relying heavily on ventilation. My doctors predicted that I would not make it through 2018. It had taken me two years to get to a point that took Stephen 20. Sadly, my scenario is the more realistic for those living with MND.

But I felt that I was not done, that my story was not complete. I felt that there was more work to be done and more work that I needed to do. I needed more time with my amazing and strong wife, Rachel, and my two beautiful daughters, Talia and Maddy.

Most people with MND die from respiratory failure due to loss of diaphragm muscle control or complications like pneumonia. Inspired by our meeting with Stephen Hawking, it seemed the next logical step was to consider life support through mechanical ventilation.

I had a laryngectomy to separate my oesophagus and wind pipes to reduce the risk of pneumonia, and a tracheostomy, which means that air can be pumped directly into my lungs through a hole in my neck. This surgery may prolong my life by years, even decades, but the MND will continue to progress.

I am recovering, very slowly, but I hope to be back at work soon. It has been very hard on myself and my family but I need to see this disease beaten into submission before I leave this world.