The graphics were created by Andrew Arnold, aka Arnie.
As far as Stephen is aware, he didn't work on any other games.
Interestingly, Stephen mentioned a completed game he wrote prior to Sir Lancelot called Attack Of The Mutant Micros. He reckons he has a tape of it somewhere so will update everyone if he finds it.
Watch out for the feature in a couple of months.
Cheers
Graeme