An unreleased track called 'Ready mix' and 'Mount Teide' are included on 'One More Time', Carl Palmer (of Emerson Lake & Palmer) 2 CDs best-of album which will be released on May 21. It's available at Amazon.co.uk. (Source: Chris Morrison via alt.music.mike-oldfield)
I first came across this when researching unreleased tracks in about 1995. David Porter informed me that he had seen this on one of the master tapes that were being collected together to compile the Elements box set.
It is believed to have been recorded in 1981/2 during the Five Miles Out sessions, which is when Mike worked with Carl on Mount Teide.
It is strange that an unreleased track turns up on a best of... but then it is one good way of ensuring that people buy the album when they probably have everything on it already.