"You charge us with having Baptists, Paedobaptists, Arminians, and Calvinists, Millenarians, Anti-Millenarians, and even Quakers. Well, are there not Paedobaptists, Arminians, Calvinists, Millenarians, Anti-Millenarians in the Establishment, and teaching too? And Quakers have been received there too: also they have been with us, and have been baptized as became them from the circumstances they were placed in. The only difference, then, on the point, is as to the existence of these various views in the minds of these amongst us. They being real Christians, we should undoubtedly feel it wrong to shut them out, and rejoice we can walk together in love." [Darby, in “The claims of the Church of England considered; being the close of a correspondence between the Rev. James Kelly, of Stillorgan, Ireland, and J.N. Darby” (1842).]

Darby didn't repudiate the charge that there were "anti-millenarians" among the brethren - so was he conceding that point? If so, who would he have been thinking of?

Darby didn't repudiate the charge that there were "anti-millenarians" among the brethren - so was he conceding that point? If so, who would he have been thinking of?

I don't think it's a matter of "conceding", in the sense that he was concedeing that persons with heretical views (such as Quakers) were welcome to break bread as any other Christian.  I think his further statement clears it up:

And Quakers have been received there too: also they have been with us, and have been baptized as became them from the circumstances they were placed in.

I take it that he is referring to those who have left their previous groups (in the case of outright heretics) and come in as any Christian.  His next statement supports that:

They being real Christians, we should undoubtedly feel it wrong to shut them out, and rejoice we can walk together in love."

So then, and completely consistent with all he ever wrote on this, Darby believed in only one basis of fellowship - that of being a Christian.  Fellowship would never be refused simply because one had different views on non-essential differences.  Calvinist?  Arminian?  Post millennial?  Amillennial?  None of these should divide us, and the early brethren received all who were real believers, unless there was some positive reason for excluding a particular person.   That might be heretical doctrine or it might be personal immorality.   

But disagreements about non-essentials was never a basis for refusing fellowship.