He was born in 1611, son of Duncan Forrester and his wife, Margaret Ramsay.

He was apprehended while preaching the Gospel in Fife, was imprisoned in St Andrews, and, on 3 August 1676, sentenced to the Bass.

Released on giving caution to appear when called, a paper found on his person revealed that on 25 May 1676, fifty-three outed ministers met for conference at Edinburgh, and took measures to maintain correspondence throughout the church in the wilderness, and to have young men brought forward for and sent out in the work of the ministry.

[6] As Mr Forrester would reveal nothing as to place or persons, he was anew sentenced to imprisonment in the Edinburgh Tolbooth "in a chamber by himself, that no person have access to him except with meat and drink, and that he be not allowed the use of pen, ink, or paper.

"[7] He was examined by the Privy Council of Scotland on 8 February 1677, indicted upon the more serious charge of "sedition" — which, however was entirely groundless — and adjudged to imprisonment in the Tolbooth of Edinburgh.