Eglass - thanks for the thought, anyway! I'm pretty sure it's not Pairpoint. My best guess at the moment is Hawkes for the cutting, but it would help to know who did the blank. One day I'll find out! Maybe.
Just an aside: hard to see it clearly, but it looks like a pattern very similar to Harvard is shown in Hadjamach, pg. 372, attributed to "Stourbridge." The only difference I can see is that the crosshatching runs horizontal/vertical rather than diagonally.