Barlow was prominent in two abortive schemes of comprehension (inclusion into the state church) set on foot in October 1667 and February 1668. The "Comprehensive Bill", based on the Declaration of Breda, was drawn up by Sir Robert Atkyns and Sir Matthew Hale, and revised and endorsed by Barlow and his friend John Wilkins. Its introduction was frustrated by a Commons declaration and the plan was finally dropped. Barlow had some part in the release of John Bunyan from Bedford gaol in 1677.