This annoys the shoot out of me. Cat Stevens / Yusuf sang this solo but using two voices. Boyzone had five members in the group but had one person sing it, using the same voice throughout. It's supposed to be a duet FGS.
Maxi Priest I think.
It *was* Jimmy Cliff first, just checked. He released it a few weeks after Cat Stevens and it made No. 8 in the chart. Cat's version was only released on LP (Tea For The Tillerman). Maxi Priest's version, being reggae-inspired, is probably more a cover of Cliff than of the original, sgtrictly speaking.
Agreed about the duet in Father and Son. It's a very clever bit of writing, and the two tunes blend extremely well. CS had a good vocal range, and the octave-apart different parts suited his voice. Boyzone's version was flat and unimaginative.