Chris,
The link to online Minutes is
here.
I've found something very interesting. I've found one mention of the date of Boulton replace Burroughs at Westminster Assemby at volume 2 of the book "The Life of John Milton: narrated in connexion with the political, ecclesiastical, and literary history of his time" by David Masson at page 516.
BURROUGHS, JEREMIAH, M.A. (Cantab.): cetat. circ. 43. His nonconforming opinions had driven him abroad, and he had been minister (along with Bridge to an English congregation at Rotterdam. Returning in 1641, he had accepted no parochial charge, but had been occupying himself as a preacher in London, more particularly at Stepney on Sunday mornings ; where he drew such large audiences and was so popular that Hugh Peters had named him "the Morning Star of Stepney." He died Nov. 1646.
To supply his place in the Assembly there was appointed (March 13, 1646-7) SAMUEL BOULTON (Cantab.), minister of St. Martin's, Ludgate. He was appointed, about the same time, to the Mastership of Christ's College, Cambridge, vacant by the death of Dr. Bainbrigge ; and he lived till 1654. This Boulton must have been well known to Milton, as they had been at Christ's College together, and had taken their degrees of B.A. and M.A. at the same time (see Vol. I. pp. 218 and 258).
You can read it at Archive Books
here