Made into the film 'Breathe', what caused Robin Cavendish to be paralysed from the neck down?

Robin Francis Cavendish (12 March 1930 – 8 August 1994) was a British advocate for disabled people, medical aid developer, and one of the longest-lived responauts in Britain. Born in Middleton, Derbyshire, Cavendish was affected by polio at the age of 28. Despite being initially given only three months to live, Cavendish, paralysed from the neck down and able to breathe only with the use of a mechanical ventilator, became a tireless advocate for disabled people, instrumental in organising the first records of the number of responauts in Britain and helping to develop numerous devices to provide independence to paralysed people.

Cavendish died on 8 August 1994 at Drayton St Leonard, Oxfordshire, England at the age of 64, becoming a medical phenomenon as one of the longest-living polio survivors in Great Britain. In their obituary of him, the Rentons stated, "To know Robin Cavendish was to know the personification of courage. Many people achieve moments of great courage, few are called on to show it continuously for 36 years."