A chance accident - a toy falling on him, while playing with his younger brother - revealed that William Richardson had a rare and aggressive tumour behind his right eye, which was becoming badly swollen.
After receiving chemotherapy in Newcastle, William and his parents Craig and Marie and younger brother Alex had just three weeks' notice to uproot and go to a clinic in Oklahoma for nine weeks.
It took two weeks to prepare for treatment once they were out there, followed by proton beam therapy every morning from Monday to Friday for four weeks. The local children's hospital also provided chemotherapy at weekends, because the cancer was so aggressive.
Luckily, William felt well throughout the treatment, which allowed the family to take trips out in the afternoons to lift their spirits.
Now, his mum Marie says William is doing wonderfully well - enjoying school, starting swimming lessons and joining the Beavers - and his medical care in Newcastle has been reduced to monitoring every few months.