The glasses are the important part, but not exactly that they hid his face. They did something else. And it has nothing to do with twins or any plot point, supernatural or otherwise.
Were his eyes sensitive to the light?
Did his eyes develop a medical condition similar to David Bowie’s?
No
No
Is the blindness connected in any way to his character getting killed off?
Is the production method (shooting each episode straight through) relevant to this solution?
No
Yes
Cue cards?
Did the glasses make some aspect of his job easier? If so, is it related to makeup / costume changes?
Was he appearing in any other shows, films, plays, etc., at the time?
Did he have any relevant medical conditions or disabilities?
Yes! You got it! David Ford had a very difficult time remembering his lines. The grueling day-to-day scripts and schedule were harder for him than most. His rumored affinity for the bottle may have made it even more of a challenge. Before the “blindness” it was obvious when he would be looking for his cue cards rather than talking directly to another character. His solution was to blind his character, thus making the need to be seen conversing directly with others unnecessary. His character in dark glasses could be looking straight ahead (at the cue cards) while conversing on screen and thus conceal his need for cards from the viewer.
In a similar vein: imagine I told you I had a script that I’d figured was ready for TV, only I then got informed that, well, look, the advertiser isn’t paying to merely get a commercial or two aired during this; they actually want a scene added, with characters talking about how much they’re enjoying the product, okay?
IMHO, there’d be nothing lateral about that; maybe I’d stamp my foot and holler about artistic integrity, but maybe I‘d just shrug and write the scene to placate that advertiser. And, what the heck: if the powers that be ever decided to redo it without that advertiser, then we could just drop that extraneous scene, right? I didn’t figure we needed it in the first place; I’d presumably be fine with an audience seeing it As I’d Intended.
Yeah, so, this is — the opposite of that. Once upon a time, there was a script the writer was content with, and he added nothing referencing this or that advertiser; each advertiser simply paid up without asking for a mention in the script, and it aired on TV just fine. And, when the time later came to take another crack at it on TV with some different actors, well, nothing got taken out, but a new scene got written in because of the lack of an advertiser.
No references to any product or whatever were involved. What was?
Did the scene break the fourth wall (i.e., acknowledge in some way that it was a TV show)?
Did the extraneous scene make some product look bad? Did any other scene in the show?
Is it to pad out the runtime, because a show with fewer commercials (of whatever sort) wouldn’t take up a full standard timeslot?
No.
Did the extraneous scene make some product look bad? Did any other scene in the show?
Not as far as I can tell.
Is it to pad out the runtime, because a show with fewer commercials (of whatever sort) wouldn’t take up a full standard timeslot?
I don’t know if this involved a standard timeslot, and so I honestly don’t know whether the overall runtime was a factor; for all I know, maybe they would’ve been happy to air it with a slightly shorter runtime than they wound up with, if it ran a little longer than they would’ve liked but they shrugged and decided to allow it anyway — or if a given scene had been deemed to be offensive or something, and if the story would’ve still made sense without it.
Was the show at all about advertising?
Nope.
To be clear, this script aired on TV without anything added to reference an advertiser. Then, the same script was filmed for TV again with different actors and a new scene was added because of the lack of an advertiser.
Assuming this is yes, how much time passed between the two broadcasts?
Did the original broadcast include live commercials with the show’s actors?
Five-and-a-half months.
No, I don’t believe so.
Were both broadcasts on the same network?
Same country?
Same language?