I've finished the run of episodes for the 'Cadfael' mysteries, and am basically ready to provide my splainin as to why Hugh Beringar looked like three different men.
Behind the scenes, there were thirteen episodes of 'Cadfael' over a four and a half year period. And during that time there were three different actors playing Undersheriff Hugh Beringar:
One Corpse Too Many
The Sanctuary Sparrow
The Leper of St Giles
The Virgin in the Ice
The Devil's Novice
A Morbid Taste for Bones
The Rose Rent
St Peter's Fair
The Raven in the Foregate
The Holy Thief
The Potter's Field
The Pilgrim of Hate
When Edith Parteger, as Ellis Peters, wrote these stories, her Hugh Beringar was one man. If there was any alteration to his appearance, then it was due to age or wounds suffered in the course of a life prone to violence.
But that world she created is not the same world which was adapted for Television. For the Toobworld Dynamic, a splainin must be found as to why the facial features and bodily attributes of Hugh Beringar changed twice over so radically.
Plastic surgery is out of the question - the stories take place in the middle of the 12th Century! Quantum Leaping in general is out - the project didn't go online with Dr. Beckett's experiment until the 1990s and he could only leap within his own lifetime.
But the quantum leap aspect about inhabiting the aura of the original, so that the replacement casts a glamour that looks the same, might come into play. And time travel as a general concept is probably at work here.
I'm thinking Time Meddlers.
Notice I made that plural. Although Shrewsbury Abbey would be the perfect place for him to hide out until he could make his escape, I don't think the Meddling Monk is responsible for this recastaway - at least not directly.
Not all Time Meddlers should be considered villainous. The agency to which Captain Jack Harkness of 'Torchwood' and Captain John Hart once belonged probably meddled in Time to put right what once went wrong. That's what Phineas Bogg did in 'Voyagers!', and in fact, I think he worked alongside the Captains. (Probably under them as well, if you know what I mean - nudge nudge wink wink!)
There's another point about this recastaway I should bring up - I don't think we can consider this splainin to be like others in the recastaway category. Usually we accept the first actor established in a role to be that of the actual character. Then we have to find the reason as to why their facial features changed so radically within the "reality" of the TV Universe.
However, in this case, I think the first two actors to portray Hugh Beringar - Pertwee and McCarthy - were the imposters, the Time Meddlers. (And by Time Meddlers, I mean that they were Time Agents like Captain Jack.) It's not until Anthony Green came on the scene in those last three episodes of 'Cadfael' that we finally meet the actual Hugh Beringar.
So why were they there in Shrewsbury, and for so many years?
Here's where it goes back to the Meddling Monk.
"The Time Meddlers"
The TARDIS arrives on an English coastline in the year 1066. Exploring, the Doctor discovers that one of his own people, the Monk, is conspiring to wipe out the Viking fleet and thus allow King Harold to face the forces of William of Normandy with a fresh army at the Battle of Hastings. [Description from The Eye Of Horus]
It is hinted that the Monk was a Gallifreyan Time Lord like the Doctor, complete with his own TARDIS. When he arrived in England in 1066, it was with the intention of diddling with the events so that the Norman Conquest failed. And with that part of the timeline foiled, the rest of it would be rejiggered - the Dark Ages would disappear and Mankind's development would have accelerated. This would mean that powered flight, telecommunications, and (Ooh! Ooh!) Television would have arrived centuries before they were supposed to.
At the same time, weapons of mass destruction like the atom bomb would have come into existence far sooner than they should have - and into a world where Mankind might not have been ready to treat such technology responsibly. (Not that we are ready now, unfortunately.) The Monk may have simply speeded up the process by which we destroy ourselves. And so the Doctor had to stop him.
Having done so, the Doctor then made it impossible for the Monk to escape the time period by altering the relative dimensions of the interior of the TARDIS; making it too tiny for him to enter the "vehicle". Unlike the TARDIS of the Doctor, the Monk's TARDIS was now smaller on the inside than it was on the outside.
It's unknown how long the Monk was trapped on Earth by this ploy, but the passage of 70 years - from the Battle of Hastings to the Siege of Shrewsbury - would be a minor hiatus.
When the Doctor left the Monk behind in 1066, he said that he might - might! - come back to rescue him from the time period. However, the Doctor was surprised to see the Monk again in "The Daleks' Master Plan". Either someone else rescued the Monk, or the Doctor did it later in his own timeline, perhaps even by one of his own regenerations.
So what if somebody else was responsible for plucking the Monk out of that era? If this is feasible, then we might have the reason as to why Time Agents were hanging about Shrewsbury Abbey - they were lying in wait for the Meddling Monk.
Being a Time Lord himself, the Monk might have had a way to disguise his presence from notice by Time Agents. As such, they probably had to enact long-term plans in tracking him down. A study of the timeline may have revealed that Shrewsbury Abbey would be the most likely place for the Monk to reveal himself. Perhaps he might have even shown up there with the intention of killing Brother Cadfael in order to alter the timeline again. With his deductive skills and worldly reasoning, Cadfael saved many people from being unjustly executed for crimes they didn't commit. These people may not have been important in themselves, but their descendants could have had an impact on the Future.
It would have been like "The Terminator": remove that ancestor, and you can change the Future. Perhaps this was something the Meddling Monk had in mind for the fate of Brother Cadfael.
Up against a foe who could hide his presence from their sensors (probably a Lectric Chamber, as seen in 'Captain Z-Ro'), the Time Agents would have had no choice but to install an Agent near Shrewsbury Abbey to keep watch over Cadfael. (Having him disguised as another monk might have been better, to keep closer guard over Cadfael, but his arsenal of weapons for such a duty might have been hard to explain. Especially with Brother Jerome snooping about!)
Study of the time period would have yielded the perfect candidate for the Time Agent to impersonate - Hugh Beringar, a nobleman who once sided with the Empress Maude in her contention for the throne of England against her kinsman Stephen. His life path could have taken two different paths, with one of them leading to his death as a traitor to the King. It will be my contention that the Time Agency decided to send in one of their own agents to impersonate Beringar in order to make certain that he was accepted back into the good graces of King Stephen after the Siege of Shrewsbury.
Sean Pertwee portrays this first Time Agent, perhaps chosen because he most closely resembled the original Hugh Beringar. Of course, his appearance would be augmented by some kind of illusionary projection device which he would wear on his person. We as the audience would see him as who he really was - just as was the case with Dr. Sam Beckett of 'Quantum Leap' - but other characters would see the glamour of the real Hugh Beringar.
Another reason I chose Time Agents over Time Meddlers - their method of time travel would be contained in wrist devices, easily disguised as leather straps and close to hand in case of emergencies. Much better than being saddled with a TARDIS, especially when the plan is a long-term infiltration.
Disguised as Hugh Beringar, this unknown Time Agent was able to work his way into becoming the Undersheriff for the area in the summer of 1138 (as seen in the episode "One Corpse Too Many"). And as such, he was able to work closely with Brother Cadfael on several mysteries; all the while with an eye on the possible arrival of the Meddling Monk.
This Time Agent lived out the life of Hugh Beringar for about three years at most (probably less), waiting for the arrival of the Meddling Monk. However, as depicted in the episode "Monk's Hood", "Hugh Beringar" was stabbed by Meurig. Although he did survive, the wound was grievous enough that he needed to be taken off the assignment.
A new Time Agent was quickly chosen to replace him, but the Agency didn't have time to find someone who was also close in appearance to the original Hugh Beringar. The illusionary device would have had to work overtime in protecting his semblance to the Undersheriff. Because it might fail at any time without "Beringar" even noticing it, this new Hugh would be constantly testing its strength with challenges to Cadfael.
We first see this happen in "The Virgin In The Ice", in which "Hugh" tests his knowledge of Cadfael's past by bringing up the topic of Cadfael's former love in the Middle East, Miriam. Knowing Cadfael's personal history from the Agency files, this Time Agent probably brought up this topic to get Cadfael in the proper frame of mind for his coming encounter with his illegitimate son, Olivier de Bretagne. (Which makes for a good splainin as to why the subject was broached in the first place; without it, the scene is just clumsy exposition!)
We see "Beringar" test their relationship again in a later episode when he gets into an argument with Cadfael. His anger seems to come out of nowhere ("Don't test our friendship, Cadfael!") but the ruse proves that Cadfael is not displaying any doubts as to his identity. The monk quickly apologizes in hopes of salvaging their friendship, and we as the audience can see the satisfied smile on the face of this second Time Agent; his disguise is still safe.
And what of the original Hugh Beringar?
He finally returns in the episode "The Holy Thief". So at some point between "The Raven In The Foregate" and "The Holy Thief", the Time Agents completed their mission and removed themselves from that time period.
We know this is the true Hugh Beringar because his relationship with Cadfael is obviously not as close as it had been. And he subscribes to the old ways - for instance, he believes in the proof of a man's guilt by dunking him in the river to see if he floats or sinks. The first two "Beringar"s would have been more modern in their thinking.
(Although the second Time Agent had a little fun at the expense of Brother Jerome's beliefs when he says "You might as well suggest the Earth moves around the Sun with as little proof!" This happens in the episode "The Virgin In The Ice", and the Time Agent might have been feeling a bit cocky that his new disguise had fooled the locals.)
Where had the True Hugh been all that time? For my splainin to work, the Agency would have had to hold him prisoner outside of Time, all the while installing new memories to keep him updated on what his life was like without him there to actually live it out. (Whatever device was used by the Agency, it was probably similar in execution to that used by Madacorp. in 'Kyle XY' when implanting new memories into Jessie XX.)
Being outside of Time, the true Hugh Beringar would not have had to be imprisoned for all the years spent by the disguised Time Agents in Shrewsbury. From his perspective, he would have been abducted, imprinted with the false memories, and returned to his 12th Century life in a matter of days at most - even though he was placed at the point in Time years later when the Time Agents abandoned the project. So he would still look as young as he did when he first arrived in Shrewsbury in 1138. (And as mentioned earlier, his true visage would not be far off from that of the Time Agent first chosen for the mission.)
As for those Time Agents, if their mission had been to capture the Meddling Monk and remove him from that era, it appears that he somehow escaped their imprisonment. (Perhaps he was disguised as Father Christmas when he broke free.) Once on his own, the Monk tracked down the Doctor as was seen in "The Daleks' Master Plan".
I have a Wish-Craft when it comes to this scenario: I'd like for the Doctor to finally meet that first Time Agent (as played by Sean Pertwee). I think he might have seen in the Agent a "younger" version of himself.......
Once more I stress that there's no way Ellis Peters would ever have conjured up something like this for the novels. But it makes for a fun splainin as to why there are three Hugh Beringars in Toobworld!
'Terminator: The Sarah Connor Chronicles'
'Whirligig' (Sorry about that, Chief!)
Brother Toby OB