This is the heartwarming moment a seven-year-old boy rang a bell to mark the end of his four-year battle with aggressive cancer.

Dressed in a suit and bright red bow tie, Nathan Mowat proudly rang the end of treatment bell at a special ceremony -- signalling he is cancer free.

Mum Gill, 36, described the moment as one of the biggest days in Nathan's battle with acute lymphoblastic leukaemia -- an aggressive cancer of the white blood cells.