I take it that A.S. is Alexander Stewart. Is G a Mr Gilpin? C.S. is of course Charles Stanley.

Is this pamphlet referenced on the last page, entitled,"A Letter relating to the recent Excommunication of Assemblies, and the ways of the Brethren in regard to Discipline, &c."-S. W. Spurr, 114 West-street, Sheffield. extant anywhere? It is often quoted in older works of Brethren History. But it seems very scarce if indeed it still survives anywhere.

I've seen something similar (I think in the CBA) but under this title:

Christian obedience not ‘ecclesiastical independency’. Letters of J. N. Darby & Mr B. Ellis relating to the refusal of Sheffield brethren to recognise a certain course of ecclesiastical discipline enacted in London, with replies on behalf of Sheffield brethren (Sheffield: S. W. Spurr, 1866).