The title for the 1983 movie The Ploughman's Lunch derives from a bit of modern lore summarized by the following bit of dialogue from near the end of the script:
Matthew: That food you're eating.
James: Yes.
Matthew: What would you call it?
James: I dunno. Ploughman's Lunch.
Matthew: Ploughman's Lunch. Traditional English fare.
James: Uh huh.
Matthew: In fact, it's the invention of an advertising campaign they ran in the early Sixties to encourage people to eat in pubs. A completely successful fabrication of the past, the Ploughman's Lunch was.
[Link.]
James: Yes.
Matthew: What would you call it?
James: I dunno. Ploughman's Lunch.
Matthew: Ploughman's Lunch. Traditional English fare.
James: Uh huh.
Matthew: In fact, it's the invention of an advertising campaign they ran in the early Sixties to encourage people to eat in pubs. A completely successful fabrication of the past, the Ploughman's Lunch was.
[Link.]
The claim that the Ploughman's Lunch, far from being a traditional part of the English culinary heritage, was merely the invention of such an advertising campaign was possible in 1983 because at the time the earliest relevant instance of the phrase listed in the Oxford English Dictionary came from 1970. Further searching in 2005-2006 was consonant with the claim, since an instance was discovered from 1960 in advertising materials associated with the Milk Marketing Board, materials designed to sell more milk in the UK in the form of British cheese.
The research, however, was far from complete. First of all, the combination of bread, cheese, and beer for the working class in Great Britain happens to far predate any advertising of these three staples together in the Sixties, and the status of the meal as pub fare is attested from in between the World Wars. Second, however, it turns out that, while the exact phrase ("the Ploughman's Lunch") may hail from a marketing campaign, that marketing campaign happened in the Fifties, not in the Sixties, and at the behest of the Cheese Bureau, not at that of the Milk Marketing Board. Furthermore, the phrase seems to have been a modification of a very similar phrase which was apparently in currency at the time, "the Ploughboy's Lunch." (Perhaps someone wanted the meal to sound more "manly.")
Whatever one may think of a national commodity board standardizing a name for a traditional meal, the notion that the Ploughman's Lunch, whether as a meal or as the name of a meal, is the result of an advertising campaign in the Sixties is false.
The notion is, in fact, itself the result of a logical fallacy which I might summarize as: the mistaking of the first extant instance of some phenomenon with the first historical instance of that same phenomenon. For a few years now I have liked to think of this error as the Ploughman's Lunch fallacy. Sometimes there are circumstances attending the first extant mention of a phenomenon which imply that it is also the first historical instance of that phenomenon, but not usually (especially in antiquity, as opposed to in modernity). In this case, while the use of terms such as "invention" or "fabrication" might make the purported origin of the Ploughman's Lunch sound like the results of critical historical inquiry, the truth is that the whole idea depends upon a recklessly uncritical dearth of historical methodology. It is one thing to admit that our first extant instance of something is all that we have (so far); it is quite another to draw inferences from that fact which necessarily entail it also being the first historical instance of that same thing.
The hard version of this fallacy, of course, is the assumption that the first extant instance of something is exactly equivalent to its first historical instance. But there is a soft version, as well, one which eschews that exact equivalence but still maintains that the first extant instance of something must be very close (whether conceptually or chronologically) to its first historical instance, that it may be fine to think there might be other instances nearby in the historical record, but to go any further afield would be folly. Someone indulging in the soft version of the above fallacy would probably be willing to give up on the Milk Marketing Board having originated the phrase in the Sixties in exchange for the Cheese Bureau having originated it in the Fifties instead; the "moral of the story" would be pretty much the same in either case. But to learn that a very similar title was actually current in at least one actual pub before even the Cheese Bureau got its hands on it is already a step beyond; and to learn that the meal itself is probably medieval in origin, and was certainly a part of pub culture before World War II, is a leap and a bound beyond even that. In fact, both versions (hard and soft) of the fallacy are fallacious. (I might add that, in my experience, both versions are also very frequently tied in to a preferred historical narrative on the part of the person buying into the fallacy; but such motivations are not an intrinsic or necessary part of the fallacy itself. Also in my experience, the fallacy tends to view all social classes through a singularly literary lens insofar as it relies heavily upon written records, even though, historically speaking, most of humanity has not left much of a written trace, and the lower classes especially are less likely to have left literary remains than the upper classes.)
Ben.