Here's a snippet of Stuart Maconie's Freak Zone from BBC 6music last week: a version of Good King Wenceslas recorded by a choir of various Top Gear stalwarts in 1970, including Soft Machine, Sonja Kristina (Curved Air) and Marc Bolan.
(112K MP3, 4.7Mb, 5:50)
Maconie's guest, "Professor Spear", goes on to explain that this rendition originally appeared in the Christmas Top Gear of 27-12-69. However that's clearly incorrect as I posted that particular show a couple of months back, and this song is not in it.
(BTW, does anyone think that Prof. Spear's words about the 27-12-69 show sound remarkably like he's reading from my earlier post?)
Thanks to Colin Ellis for letting me know about this show.