by Andrew Eldritch in Hamburg in 1986 with a Casio CZ-101 synthesizer.
The track appears on various bootlegs like ECHOES VOL. II or 1983 - 1986.
A 1:12 min. demo version of Flood I does exist as well.
What was used for bootlegs is however the longer Flood II demo which lasts around 3:32 min.