Well we have been pretty quiet so I will toss in what I have read.
My sources are a beat up Vol 3 of Levine's Guide, Best if Knife World vols 1 2 and 3 (Mark Zalesky located a copy of the rare vol 1 for me 4 or 5 years ago.) and articles read over the years. I have also read a couple of Sheffield books that touched on the subject. Goins was also a little help. Once Bernard's book pointed me there.
Guys, Levine's guide is a must for any knife-nut and IMHO Knife World now edited by Mark is also a must. (The prices for both are a fantastic deal if you have the time to read them.)
Ok mixing it up from those sources and a thought or two that might even be my own:
We have a Cutler family in Sheffield during the 16 and 17 hundreds. The name (you guessed by now) is Barlow. According to Levine's Guide the first of the family to obtain noteriety was Edward Barlow. He was elected master of the Cutler's Guild in 1653 according to the same source. Goins says that Obediah Barlow was the first Barlow that made a name of themselves via the barlow knife. He set up business in 1667. I am going with Bernards 1653 date and Edward on that one.

.
Obediah's family kept things going cutlery wise for several generations until 1789 when geat grandson John Jr. (the last of the line) passed away.
There is another branch of the family that Bernard mentions "Samuel Barlow". He was from Neepsend which is near Sheffield. In 1787 the knives of Samuel were trademarked with a sideways "Z". (sorry I do not know the ascii code for that.) Samuel made knives into the 1830's and added the family name "Barlow" to his stamp in 1878.
In talking a little with my dad who is 77 (still running his small business and going to work every day and quite guillty of passing this hobby on to me.

) my understanding is that when he was a kid and the topic of knives came up, Barlows were usually the center of the conversation. He says they were a very popular pattern for folks of all ages during the 20's and 30's. Maybe even one of the most popular patterns.
I am guessing that since that was the period of the Great Depression that quite a few inexpensive varieties were available. Makes sense to me that since they only have a bolster at one end it would follow that the Barlow pattern could be cheaply manufactured so that they could be affordable in those tough times. (I am not sure if one of my readings planted this thought or if I made it up so take it for what it is worth - a plug nickel or therabouts, but at least it makes some sense.)
The pattern is characterized by a blade or blades pivoting from one long bolstered end and yes there are some that can be found with a razor master blade (the kind with the finger notch cut out of the tip of the blade). If a second blade is present it is usually a pen. Other master shapes (Spey, Clip, Sheepsfoot or Spear) are also found on some examples.
That about taps me out, but I am sure others will chime in with time on what they know and have read.