This is Part 1 of 2, containing the Kyrie, the Gloria, and the Credo:
And here's Part 2 - the Sanctus, Benedictus, and Agnus Dei:
The singers here are The Choir of Westminster Cathedral. From the YouTube page:
If you're interested in purchasing the CD, it is available at either Arkivmusic:
Or at Amazon:
The CD also includes other choral works by Vaughan Williams, and Mass by Judith Bingham.