Looks like Masashi Yamamoto
Ah thank you!
The reason I asked is because it was probably the best stainless* I've ever sharpened, something about that knife really did it for me. Internet tells me he uses something called 'VS1' which I've never heard of before. Will have to research.
Poor guy who brought it in was new in London (think he might have been Canadian) and had a trial at a trendy restaurant the next day. He'd taken his knives to a well-known company here who offer sharpening, and they'd completely screwed his two gyuto. I was genuinely shocked at the condition they'd given them back to him in; stupidly fat bte, and with zero core steel exposure.
Happily though I did a f-ing amazing job, thinning them right down and rebuilding the geometry. That Masashi in particular I really liked, if I hadn't tried etching it I would've guessed the core was high quality carbon steel.
* Probably 'semi-stainless' I think, given what happened with the etch. I polished it out after cos it didn't look great, but there was some distinction between core and cladding.