Dafydd goes down a storm at the monthly gigs he stages at Pendine Park’s Bryn Seiont Newydd care home in Caernarfon which specialises in looking after people with dementia.
Remarkably, even residents unable to hold a conversation or in some cases remember their own names are able to remember the words and sing along with him.
Experts say that music is one of the first things people learn and one of the last things they lose when their memory is destroyed by dementia.
Staff at Bryn Seiont are also big fans of the legendary singer whose performances have an uplifting effect on the residents and the carers who work there.
One of their favourite numbers is Yma o Hyd (Still Here) which is the song that catapulted Dafydd to unprecedented chart success.
The song had already been adopted by the Scarlets rugby region and is played before the start of home matches and it is often sung by fans at Wrexham AFC’s home ground, the Racecourse.
More bizarrely, it has now also been translated into Norwegian and is sung by a choir in Norway.
It was originally released in 1983 before climbing to the top of the iTunes chart nearly 40 years later thanks to an online campaign inspired by a successful attempt in Ireland to get the Irish rebel song “Come out Ye Black and Tans” to the top of the chart.
Yma o Hyd was part of Dafydd’s set at Bryn Seiont which also included hymns, folk songs and a few of his other classic songs.
Dafydd, who lives five minutes away from the care home, said: “Several different songs break through and lights up the memory for different reasons. I enjoy this experience. It’s amazing that people who can’t remember their own names can remember words to the songs.
“Someone explained to me that’s the last part of the brain to go, the bit that remember things like words of songs, and I find that very interesting.
“You will meet some people who are unable to have a conversation who will sing every word to a song, and that’s remarkable. I get a great deal of pleasure from sessions like this.
“It’s good that a place like Bryn Seiont Newydd exists for the residents.”
Dafydd, a former county councillor who co-founded the record company, Sain, and is a former president of Plaid Cymru, was stunned by Yma o Hyd’s recent success in the charts.
He said: “It’s a bit surreal. It shows the power of social media, that’s one thing, because it was through Twitter and Facebook, and it happened faster than anyone had envisaged.
“What’s interesting by now is that the song has crossed the language barrier. It has become a rugby song and a football song, and therefore a lot of people know about it, and acknowledge it as some sort of a second national anthem, and the idea took hold and it went up within a few days.
“There’s something special about the song that catches people’s imaginations.
“There is something in it that comes over without even understanding the words. There is something that sparks people in the song.
“A lot of people contact me from other countries. It was recorded some years ago in Breton and there are several English versions.
“There have been several versions abroad, and over the years they have gotten in touch and have asked for permission to use it.
“It gets used a bit by the Welsh in North America, Chicago Taffia, and there is a new society now, the New York Welsh who have adopted it as a signature tune, so the song does travel.
“It is an anthem for anybody who feels they have had a hard time and has come through it and overcome it against the odds. That’s the message, and that is relevant to so many different things.
Pendine Park’s Musician in Residence, Nia Davies Williams, was thrilled to see how Dafydd’s songs evoked memories in residents with dementia.
She said: “We get a lot of music in but it’s voice that is important, and Dafydd’s voice is so well known so his songs have stuck in the memory
“The families are invited to come as well and it’s nice for them to see their relatives singing these songs.
“It’s nice because you see a little glimpse of how they were before. They really enjoy it and their problems are behind them for a little while.
“I’ve seen families in tears singing this song here. It’s a way of taking a stand, despite everyone and everything. It also inspires people beyond Wales.”
Bryn Seiont manager Sandra Evans: “We are very grateful to Dafydd because his gigs bring so much joy to our residents and their families.
“The arts in general and music in particular are central to daily life at all of Pendine Parks care homes and we are extremely fortunate to have a living legend right on our doorstep here in Caernarfon.”