Thomas Ellwood may well have been a friend of Milton's but, Christopher Hill in his book Milton and the English Revolution (1977) suggests that Milton was not an enthusiast of Quaker ideas;
"I do not intend to suggest that Milton belonged to any ofthese groups, that he was a Leveller, a Ranter, a Muggletonian or an early [i.e. pre-pacifist] Quaker. But . . . .their ideas illuminatehis and may well have influenced him, both positively and negatively."
"By 1660 Milton would have criticized . . . Quakers, on these grounds: they ignored the world as it really is, in all its brutality: they were fundamentally unserious, as self-regarding as a modern 'hippie'."
"The picture of Milton subsiding into a genial and pacifist old age,in which all conflicts are mental only, is a piece of twentieth-century sentimentalism which the seventeenth century texts donot justify."