Christmas is an opportunity to rejoice and to count your blessings – but it’s also an opportunity to pause awhile, and perhaps to contemplate sorrow: to think of our departed loved ones or those who are suffering in life for whatever reason.

This is also the simple and powerful message of the heartfelt documentary Anfonaf Angel: Côr Rhys Meirion, which airs on S4C on Boxing Day and follows Porthmadog singer Rhys.

At the heart of the programme is the fact that it’s 10 years since Robat Arwyn and Hywel Gwynfryn composed the special and comforting song, Anfonaf Angel, back in 2008.

Since then, the song has grown to become one of the most popular songs in Wales, and a powerful and therapeutic anthem for all who need comfort during dark periods – all this makes perfect sense, given that Hywel Gwynfryn wrote it at a time when he was feeling lonely, low and very far from home.

Another person with an emotional connection to the song of course is Rhys Meirion, and after losing his sister Elen suddenly and unexpectedly in April 2012, he gathered the strength from somewhere to sing it during the opening concert of the Urdd Eisteddfod in Snowdonia, six weeks later.

“During the concert, the place was full and I started to regret agreeing to sing, but when I stepped onto the stage, something came over me – a weight was lifted off my shoulders and it became effortless to sing,” he said.

“That’s the simple power of the song, and the therapy of singing, and I wanted to share this with others.”

And so – with the blessing of the song’s original composer, Robat Arwyn – a four-week challenge was born to create a new arrangement of the song, and to form a special choir comprised of people who have needed an angel themselves at one time or another; the culmination would be a day of recording in the Sain studio in Llandwrog.

See this week’s north feature for the full story, in shops and online on Thursday