As we were looking into The Mermaid and the Crown, we chanced across a series of unreleased titles from Mountain Valley Software that was ran by Brian J Betts during the early-mid 1980s.
This was one of five titles in total which were never fully finished, but thanks to Jacob from CASA Solution archive and other members of the forum, the games were all preserved and entries added at http://www.brilliantbehaviour.com.au/resources/marcus/list.html
We are just adding entries into the GTW64 archive, but hope to learn more about this particular adventure very soon.
In the meantime, you can download and check for yourself, but if you have any information about it – please do let us know.
Contributions: CASA Solution archive