DO NOT FORSAKE ME,
"I AM NOT
RANKED 13th Considering McGoohans absence during the production this episode isn't as bad as many describe it. Quite awful the Seltzmann-machine and the reverse process, hopefully intended as a caricature on those out of Dr. Frankensteins lab. But overall an episode of many missed chances.
Hardly anyone who'd like this episode with the original, rather poetic title "Do Not Forsake Me, Oh My Darling" or, respectively, that almost teutonically exact equation "2:2=2". The original working title was "Face Unknown". This episode bears the stigma that it's ever been condemned by many commentators as being utter rubbish, "a woesome attempt to redefine the series as a typical spy thriller, but with simply unbelievable science fiction in context", as the Anorakzone writer  says, with bad production values and wretched acting; somewhat understandable but it isn't the whole truth.
From the start the mind of Number Six is in the body of another man, played by Nigel Stock. It is the intention of the Village responsibles to coerce Number Six into cooperation and to detect Professor Seltzmann, the inventor of that piece of machinery as he's the only one with the knowledge to perform the
TOUCH OF BOND, JAMES BOND HERE. WHO'S THE MAN WITH THE "FACE UNKNOWN"
(ORIGINAL TITLE)? NUMBER SIX, IN THE BODY OF A DIFFERENT MAN,
ENCOUNTERS HIS EX-FIANCÉE - A TRUCLKOAD FULL OF POTENTIAL DRAMA, BUT NOT HERE.
reverse process. So Number Six has to make his way to Austria where Seltzman is supposed to be living. It was taken for granted that the Prisoner would (be) return(ed) to the Village.
It is not known who brought in the song title from the Fred Zinnemann noble western HIGH NOON (1952). Ian L. Rakoff said that this would have been the title of his "Living In Harmony" draft. It is probable that copyright considerations played a role because the story underwent substantial reworking before the now familiar shape emerged.
Vincent Tilsley was the author of this episode. During the 2003 Prisoner convention he told about the way his script was handled and that he had had mixed feelings about it. Because the task here was to create a convincing PRISONER story without having the principal actor present. Patrick McGoohan was in the USA for his Hollywood debut movie, the John Sturges film ICE STATION ZEBRA. Back home it was decided to end the series after the completion of 17 episodes.
The idea of the mind transfer was a hard undertaking. Tilsley delivered the script of "Forsake" hoping he'd receive an invitation to a discussion about it (together with Tomblin, Markstein, McGoohan?) in order to get
the threads and the whole story improved. As a result he hoped to achieve a conclusive episode. But Tilsley ever happend. Neither did he know if his script had been rejected nor if it had indeed been turned into a film without notifying him. Eventually, when he heard this episode was being screened and he was watching it on television he almost failed to identify it as "his" episode. McGoohan was totally dissatisfied with it. Probably the script was rewritten by David Tomblin, the story thereby losing so much of its initial meat as to enforce a title change from "Face Unknown" to "Do Not Forsake Me, Oh My Darling". And maybe, already working on the subsequent episode that he was going to direct, too, Tomblin did have something in his mind: the western parable "Living In Harmony".
Of Tilsley's concept it's quintessentially the mind transfer which remained solely intact. In one of the previous SIX-OF-ONE society magazines the two episode scripts "Face Unknown" and "Do Not Forsake Me, Oh My Darling" were compared to each other. According to this survey Tilsley's "Face Unkown" was much better than the final work. Number Six' resignation was at the centre of it and the letter he later dashes on his superior's desk. He receives a treatment in the "room of oblivion" and he, now in the body of "the Colonel" whose name in Tilsley's script is Oscar, is sent back to the day of his resignation where he experiences the important hours that lead him to his decision as a matter of conscience. A regression therapy of that kind can be found very similarly in the episode "Once Upon A Time" where there is an "Embryo Room" as the central place of the action. One musn't forget, however, that this episode had in fact been produced many weeks earlier - written and directed by McGoohan himself; a reason to reject it?
"Forsake" is believed by some to have been the first episode of a second season. Of all, it is the only episode to have a so called pre-credit sequence, something which is quite popular as a dramatic device to get the TV audience hooked and keep the interest alive during the following commercial break right before the start of the actual credit sequence. And indeed, this intro is really good, worth a thriller and intriguing, makes you want to get more. Moreover, the episode offers a sequence of (albeit only stock) footage of a journey through Europe by car which lends an ample ambience to it, a taste of Bond, James Bond here.
And there is one curious detail, to say the least, about Number Six who, as a private person, is almost inexistent. That he is supposed to have been engaged for some time to Janet, his former superior's daughter. This would have made a delicate relationship and cast a special light on his abduction and the department or people of his former department as they were almost certainly involved in it, judging by what we witness in "The Chimes Of Big Ben" and "Many Happy Returns". But this red herring is not picked up here. Also, it is understandable that those individuals responsible for the affair surrounding Number Six wouldn't be determined all to clearly and thus would be left in the dark. Number Six has to prove to Janet, rather technically, it's really him who she meets. Either way. Also, the machine required for the reverse process of this mind transfer would have made for a good MacGuffin  here.
One of the many squandered opportunities that would make up an intriguing storyline: the exploration of the apparently long-lasting relationship of Seltzman and Number Six, hinted at in the pre-credit sequence, as David Stimpson has pointed out: "I've been of the opinion that Seltzman had had something to do with the Prisoner's resignation. Because only the Prisoner knew where Seltzman was, that suggests he was shielding him. Also the Prisoner had written to Seltzman about a year before, which was close to the time the Prisoner resigned. And about the same time the Prisoner had left a roll of film at the camera shop." 
A potential dramatic gold mine it would have been. Sadly, it ends up as the pursuit of a machine, a case from the 1950s SF-trash props department. But the script doesn't take advantage of the constellation and nothing ensues with regard to whatever drama, except that Nigel Stock, as Number Six in the body of a stranger, is allowed to kiss Zena Walker. Something McGoohan would have detested.
Better perhaps this episode had never existed. One could have taken Moris Farhi's script instead which almost made it into production, but in the end it didn't. However, all shortcomings put aside, this is not the weakest episode of all. But for reasons other than many may think.
Read the episode appreciations on this website!
Hugo Schuster as Prof Seltzman, with a strong German accent, as a scientist is basically out-of-date, more 19th centurey than 1960, a lone-inventor type. His composure is a little stiff but he should be excused for being so considering the circumstances. When he learns from Number Six in the body of the Colonel about the ploy his invention has been used for he is really concerned ("my poor young friend..."). And Number Six' line from "The Schizoid Man" rings in one's mind: "The trouble with science is that it can be perverted." What remains, the allegorical flower, has to be found under the weeds.
The name itself is German or Austrian and because of his first name being Jacob he could be a Jew: Professor Seltzman. Apart from this, the character and actor Hugo Schuster's appearance in general don't do less than to insinuate the parallel Albert Einstein, something that would certainly be welcome by the script here.
Number Two, upon the encounter with Seltzman, intentionally uses the expression "Heil!" which was the common German salute to the "Führer" during the "Third Reich" and also his typical hand gesture. Why this? This little instance might hint to a darker past.
Number Two certainly knows about Seltzman and his past. What if Seltzman had been suffering from Nazi terror? In reminding Seltzman of what had happened, actually threatening him, Number Two then would employ questionable but arguably cynical methods in order to make the professor work for him.
When Tilsley was told the German title "2:2=2" he was amazed but kind of liked that non-working equation, that the title wasn't so far off as it appeared at first glance. Nevertheless, there was his overall feeling of discomfort that this episode just isn't "his" episode. On the other hand, his name as the author has been connected with this episode ever since. And this is surely more than nothing.
 Anorakzone website: http://www.anorakzone.com/prisoner/
 David Stimpson on his blog, Dec. 12th, 2012
 "MacGuffin" is an element in films or television series which in itself is quite unimportant and does hardly more than propel the story action. It could be an important document or an invention that several characters are after. It is said that film director Alfred Hitchcock first coined the term. A "MacGuffin" is at the heart of many of his films, the most famous probably being the stolen money from PSYCHO.
 In an email exchange with this author in 2016