Oh, this is an interesting one! The credits currently in base are:
Garry Hughes (UK)
Jas C. Brooke (UK)
Lyndon Brooke (UK)
Jas C. Brooke is a match, so, we are fine there.
Lyndon Brooke is the author of the loading screen (signature LND)
Garry Hughes is the author of the Amstrad version, so that's probably why he is credited.
Jez Nelson = Jeremy Lenson, part of Binary Design.