This Easter hymn by Pamela Stotter first appeared in Hymns Old and New for the Irish Church in 1977, and was printed in Alleluia! Amen in 1978, and the UK Celebration Hymnal for Everyone also.
It is set to the tune GELOBT SEI GOTT by 15th century German composer Melchior Vulpius which was first published in 1609.
The same tune is used for hymn "Good Christians All, Rejoice and Sing" by Cyril A. Alington (1872-1955) which was published in 1925, and which has a very similar structure to "Christ is Alive".
Brian Wren's hymn "Christ is alive, let Christians sing" is a totally unrelated work