However many years “A Christmas Celtic Sojourn” lasts – and it’s about to hit 19 – there’s little doubt that the 2020 and 2021 editions will loom large in the collective memories of those involved in the music-song-dance-and-storytelling production, perhaps none more so than the show’s creator and guiding spirit, Brian O’Donovan. In 2020, with Covid-19 an overwhelming concern,