I've also just found Mark Knight's peformance in "The Bill" (1994), the episode is called "He Who Waits" and it was more than likely made in between Series 7 and 8.
He plays a thuggish character named "Mick Hawkins", I wonder why he always gets to play the bad guys.
Remarkable. Many thanks for tracking this down. It turns out that Lawrence Werber's own 1990s appearance on The Bill is also on YouTube (from 5:58 in this video). The early '90s, for me, were the golden era of The Bill.
This is Cliff Barry's performance in a 2002 episode, he plays a character called Jim Weller, you can see him at 1:36. This is Lissard's first of 2 brushes with "The Bill" team and it's not just him it's Lord Fear and Cedric as well. I tell you something The Opposition have had a tough time post-1994.
I just found this completely by accident - an earlier episode of The Bill in which Mark Knight appears! It's 'Joyride' from January 1992, and I'm guessing *this* is the one they mentioned in The Quest, rather than 'He Who Waits' which aired a couple of years later. Mark can be seen at 7:06 and 7:44.
Also watch out for TimeBusters villain Andy Powrie (Bill Cashmore's writing partner) at 23:17, and Terry "Davros" Molloy as the kid's probation officer at 13:16!
.....Annnnd look what I've just found later in the same series! Also mentioned in The Quest, here's Adrian Neil (Ridolfo) as a casualty doctor in the episode 'Up All Night' from June 1992. He appears right after the opening credits at 0:26, with further scenes at 2:20 and 3:35.
That's twice Tom Karol played a supermarket manager dealing with shoplifters! (The link to his earlier episode doesn't work any more, but it can be seen here now.) Is it meant to be the same character revisited, or was he just a bit typecast?!