In the mid-80s, HIV/Aids terrified the world because of a lack of understanding as well as misinformation.

In April 1987, Princess Diana opened the UK's first purpose built HIV/Aids unit that exclusively cared for patients infected with the virus, at London Middlesex Hospital.

In front of the world's media, Princess Diana shook the hand of a man suffering with the illness.

She did so without gloves, publicly challenging the notion that HIV/Aids was passed from person to person by touch.

She showed in a single gesture that this was a condition needing compassion and understanding, not fear and ignorance.

John O'Reilly was a nurse on the ward at the time of the Princess of Wales' visit.

He spoke to Witness about a landmark moment in the fight against HIV/Aids.

Witness: The stories of our times told by the people who were there.