Brenda first fell in love with Vietnam in 1995 while taking part in a charity bike ride with her husband Baz. Sadly Baz suffered a heart attack in the same year. He was just 55.
He had been taking part in a charity swim to raise money for the Vietnemese children they had seen; children with severe disabilities and birth defects caused by Agent Orange, a dangerous chemical left in the soil and water supply after the Vietnam War.
Heartbroken Brenda planned one more visit to Vietnam in her husband's memory. But while volunteering at an orphanage, she fell in love with brave Min Anh, who was dumped as a baby because of his scaly skin and nicknamed Ka - or Fish Boy - by other orphans.
It is likely that Min Anh's painful skin condition is the result of Agent Orange infection.
"All he wanted to do was sit in my lap," recalls Brenda of their first meeting. "I sat there for a couple of hours and didn't want to move. I just fell in love with him and it's been like that ever since."
For the last 15 years Brenda, now 78, from Benfleet, Essex, has returned to see the brave little boy. The pair found a way of communicating, even though Min Anh, now 18, doesn't speak English, and Brenda knows little Vietnamese.
The determined widow, who has three grown-up daughters and five grandchildren, took on hospital authorities who left Min Anh tied to his bed for hours because they didn't know how to treat him.
"When I first went to see him at Tu Du Hospital, he was tied up from morning to night, so he wouldn't scratch himself," she says.
"The staff didn't know how to help him. I hated to see him like that, without any toys or amusement."
But Brenda's persistence paid off, and staff allowed the kindly English lady to untie Min Anh and take him out for day trips around Ho Chi Min City.
Brenda stayed for three months every year and she was the only person allowed to take Min Anh out.
Year after year, over 15 years, their extraordinary friendship grew stronger as together they went to shops, restaurants and on motorbike rides around Ho Chi Min City.
She says: "Just walking around the supermarket is like a treat to Min Anh because the cold air soothes his skin.
When we got back to the ward, he'd walk back to his bed and tie himself up again because he was used to it.
Brenda, a former secretary who has no medical knowledge, spent years trying to find a doctor to diagnose Min Anh's skin condition but had no idea where to start.
The documentary, The Boy They Call Fish, follows Brenda's most recent visit to Vietnam in early 2012, as an expert dermatologist is called in to try to diagnose and treat Min Anh. Min Anh has turned 18 and she wants to be sure the boy she thinks of as her son has a happier future.
Brenda told her local paper: "I'm so pleased this documentary has been made as hopefully millions of people will see it.
"If it means someone out there can help Min Ahh then it's wonderful.
He is so special to me. Every time I go out there his face lights up.
"If I take him to the supermarket you'd think I was taking him to Disneyland.
"He doesn't get much attention or love. As I had to leave on this last trip I said to him in Vietnamese 'I love you Min Anh and I'll be back soon to see you'.
"He replied, 'I love you too. I understand'.
"He is the light of my life. He has endured so much and with so little love in his life.
"Hopefully this will change once the world learns of his plight."
The Boy They Call Fish airs on Channel 5 at 9pm on June 21