That would be the The Economist Group, and by extension it's owners. Had it been a stock company with thousands or millions stockholders it would be safer to assume that they most likely doesn't hold that much influence over the editorial content, but I believe The Economist Groups only have a handful stockholders.

Ideally I'd say that "they" are the editors, but we don't know what level of influence the owners have, so "they" could be the Cadbury family.

Yes, I'm familiar. Based on the drivel that comes out of the Economist on a regular basis, I've long made the conclusion that "they" and whomever their close friends are/they vacation with are the "editors". I don't think it's a remarkable claim. I'm not expecting to see any WaPo articles criticizing Amazon anytime soon, either.