Toward the latter end of this assembly, upon the arrival of the commissioners from the parliament and assembly at Westminster, the Scots assembly, by an act of session 14, commissioned Messrs. Henderson, Douglas, Rutherford, Bailey and Gillespie ministers, John earl of Cassils, John lord Maitland, and Sir Archibald Johnston of Warriston, ruling elders, or any three of them, whereof two should be ministers, "to repair to the kingdom of England, and there to deliver the declaration sent to the parliament of England, and the letter sent to the assembly of divines, now sitting in that kingdom, and to propound, consult, treat and conclude with that assembly, or any commissioner deputed, or any committee or commissioner deputed by the house of parliament, in all matters which may further the union of this island, in one form of church-government, one confession of faith, one catechism, one directory for the worship of God, according to the instructions they have received from the assembly, or shall receive from time to time hereafter, from the commissioners of the assembly deputed for that effect."--This commission was again renewed by several acts of the subsequent assemblies, till the year 1648.--And it appears, that lord Warriston did not only use all diligence as a member of the Westminster assembly, for bringing about the uniformity of religion in worship, discipline and government, but also, for some time, he sat as a member of the English parliament, for concerting such methods as might bring about a firm and lasting peace betwixt the two kingdoms afterward; which is, and was reckoned a most noble piece of service both to church and state in those days; yet we shall find it accounted high treason in this worthy man afterward. Lord Warriston had, for his upright and faithful dealing, in the many important matters committed to his charge, received many marks of favour and dignity, both from church and state; and to crown all the rest, the Scots parliament in 1646, made an act, appointing his commission to be lord advocate, with the conduct of the committee of London and Newcastle, and the general officers of the army: all which evidence, what a noble hand he had in carrying on that blessed work of reformation.