Something else worth mentioning is that they use Eng Crystal Malt not C60.
English Crystal (Caramel Malt) 37 L Also known as CaraStan, use 5 to 20% of our English Crystal to add color and a full, toffee/sweet flavor to Bitters, Pale Ales and Porters.
I'm gonna go ahead and say they use C60, not C37. "English Crystal" comes in many different degrees of color, not just 37. The Malt101 page is a basic, old and imprecise reference and the posted recipe comes from the master brewer at SN. The SN website actually reads "English Caramel" and my interpretation is that they are alluding to the fact that the caramel malt used is produced by a UK maltster rather than a domestic one.
For example: https://www.brewerss....com/Crisp.html
You can see that Crisp, and English maltster produces several types of Crystal malt. From C15-C120 all of those Crisp Crystal malts could be called "English Crystal" or "English Caramel". I think CaraStan is a specific English Crystal in the range of 30-40*L, which might actually be a trademark brand name but not certain about that, some maltsters give their malts trade names rather than market them with generic malt names.
As an example of the imprecision of that Malt101 page, it lists Bamburg smoked malt as a Belgian malt. Bamberg is in Bavaria, Germany and is spelled with an "e" not a "u". Also, it lists Black Patent Malt as American, the whole "patent" thing with Black Malt is an English patent from like 200 years ago, it's not an American invention.