I have one Red Fleece OCBD - bought at a factory outlet in Florida.

Basically it's a modern cut shirt. I sized up from a medium. I don't think they do actual collar sizes - but I'm not 100% sure.

Plus points are the third collar button and locker loop.  The cloth is also very good. As it's designed to be trimmer the shirt has much smaller collars so you don't get the roll.

Its target audience is similar to the guys who were buying Rugby

As I sized up the neck line is baggier than I'd like but the price was too good to pass on.

I have a Mercer shirt.  It’s good.  I didn’t go with Oxford cloth, though, so I’m not sure how their OCBD would stack up against others. I too had them use a smaller body than they usually do - and it worked (though I could also see the larger body working too). I think their baggy sizing might come from a 1980’s sensibility.

Thanks for the heads up! Today I received a crazy 1969 dead stock paisley button down (Arrow Cum Laude label). I don’t know if I can ever wear it- it’s pretty extreme and the cream background is too yellow for my coloring. But it’s a nice artifact from my childhood. And- it fits, which is a miracle.