A candle is placed at the front of Downing Street as the building is lit up blue to mark the 72nd anniversary of the National Health Service (NHS) in London, Britain on July 4, 2020. According to local media, dozens of landmarks across the country were lit up blue to mark 72 years since the founding of the NHS. (Photos: Xinhua)

A candle is placed at the front of Downing Street as the building is lit up blue to mark the 72nd anniversary of the National Health Service (NHS) in London, Britain on July 4, 2020. According to local media, dozens of landmarks across the country were lit up blue to mark 72 years since the founding of the NHS.

A member of staff places a candle at the front of Downing Street as the building is lit up blue to mark the 72nd anniversary of the National Health Service (NHS) in London, Britain on July 4, 2020. According to local media, dozens of landmarks across the country were lit up blue to mark 72 years since the founding of the NHS. (Photo by Ray Tang/Xinhua)

The London Eye is lit up blue to mark the 72nd anniversary of the National Health Service (NHS) in London, Britain on July 4, 2020. According to local media, dozens of landmarks across the country were lit up blue to mark 72 years since the founding of the NHS.

A candle is placed at the front of Downing Street as the building is lit up blue to mark the 72nd anniversary of the National Health Service (NHS) in London, Britain on July 4, 2020. According to local media, dozens of landmarks across the country were lit up blue to mark 72 years since the founding of the NHS.

A candle is placed at the front of Downing Street as the building is lit up blue to mark the 72nd anniversary of the National Health Service (NHS) in London, Britain on July 4, 2020. According to local media, dozens of landmarks across the country were lit up blue to mark 72 years since the founding of the NHS.