By Lynette Horsburgh

Copyright bbc

Mr Davies, who worked at Network Rail before his diagnosis, said he was relatively fit with no health conditions when he “collapsed out of the blue”.

“It took months to get to my diagnosis and my initial MRI scan didn’t spot the tumour,” he said.

“My symptoms worsened over about three months including severe headaches, my speech became affected as well as my balance and I was getting confused.”

The father-of-two continued: “If helping with this research could mean someone like me can be diagnosed sooner, it offers real hope for the future.”

Mr Davies’ wife Emma said it was a “really horrible time for us”.

She said if a simple tear test could be used to bring a diagnosis forward it “would improve that awful time for so many others in the future”.

Thanks to nearly £500,000 funding from Stand Up To Cancer – a joint fundraising campaign from Cancer Research UK and Channel 4 – the study led by scientists at the University of Manchester has expanded to include larger-scale trials.