Demo has been circulating on Internet for a couple of years. The 15 first songs on Servants of Chaos are demos recorded between July 1978 and Sept 1980. I have not seen any definitive answer as to which of those, or if any, are taken from the 1979 demo record.
Does the 1979 demo really exist? There has has been a demo circulating on the web for some time, but whether it's real or just songs taken from Servants of Chaos is another question. If it is real, then about either half of the songs on it has to be different versions than those appearing on Servants, or the 1979 demo is actually from 1980 or later.
If it exists, in what format was it released on? The sleeve shown here is the common sleeve that is shown together with the demos. The sleeve looks like a vinyl sleeve and not a tape sleeve. Does that mean that Cirith Ungol put out a demo on vinyl in 1979??