LONDON (Reuters) - A dedicated doctor who came out of retirement to help Britain’s National Health Service (NHS) cope with the coronavirus outbreak has died of the disease, his son has said.

Alfa Saadu, 68, who immigrated to Britain from Nigeria and had a long and successful career in NHS hospitals across London, died on Tuesday after suffering from the COVID-19 disease for two weeks, Dani Saadu said.

“My dad was a living legend, worked for the NHS for nearly 40 years saving people’s lives here and in Africa. Up until he got sick, he was still working part-time saving people,” the doctor’s son said in a post on social media, quoted by HuffPost.

Thousands of retired doctors and nurses in Britain have returned to work in response to a government appeal for help for the NHS, which was already suffering from staff shortages before the crisis.

Founded after World War Two to provide free healthcare for everyone living in Britain, the NHS and the values it represents are a unifying force in society. “Protect the NHS” is one of the government’s core messages to the public amid a national lockdown.

Britain has reported 2,352 deaths from COVID-19 and 29,474 confirmed cases.

Alfa Saadu had remained close to his family and community in Kwara State in central Nigeria, where he held the traditional title of Galadima of his hometown of Pategi.

He was mourned by senior figures including the governor of Kwara, Abdulrahman Abdulrazaq, who said the doctor had made “tremendous contributions” to the public good.

“As a public health expert, he saved many lives in London as he did across Africa,” the governor said. “He will be sorely missed.”