The game would be later be distributed by companies such as Recreation Re-creation, PK Computer Graphics, The Guild and The Adventure Workshop.
The adventure was ported to the Spectrum by The Guild.
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The screenshot says "Converted to Spectrum using Graphic Adventure Creator", so was there an earlier non-GAC version of the game for another computer?
There is mention of a BBC text adventure game by this name here: http://www.acornelectron.co.uk/info/alligata/i-crow.html, and a solution for one here: http://www.stairwaytohell.com/gamehelp/index.html but I can't be sure it's the same game.
It's definitely not the Alligata game of the same name. As that one was based in 1980s London and this one appears to be fantasy.
The game would've originally been released on Amstrad, GACed by the author, as with his other games. The reference in the screenshot is merely crediting GAC as the tool that was also used by Pegasus Software (Tony Collins) to port the game to the Speccy.