Right you are tostadosunidos. I have a Columbia LP I bought new in 1970 of a live solo piano performance (recorded in the 1950's, I believe) of the original composition. A nice alternative to the orchestrated version.
What terrible news.   He was my musical hero.  I have played ELP's first album more than any other in my collection.  Take a Pebble.  What a gem of a song.   So sorry....
-John
jsd - 2016 is certainly off to a start as a terrible year for losses among popular musicians...not that 2015 was so good.  Anyway, while I can't say I've played ELP's first the most of anything in my collection, I can say I do like it a lot and will still listen to it.  I can well remember first hearing it just after it came out back in '70 or '71; had never heard anything like it up to that point.  Take a Pebble is a standout track.  I like Greg Lake's vocals and his song-writing (Still...You Turn Me On is another good Lake composition from BSS).   Wish I could find an SACD of ELP's first!