Wyvill strongly disapproved of the subsequent war with France, to which he attributed industrial distress in Yorkshire, and this completed his alienation from Pitt. In 1793 Wyvill published in pamphlet form correspondence that had passed between them. Some supplementary letters appeared at Newcastle in a further brochure, and both had a large sale. Wyvill attached himself to the extreme Whig opposition, and he defended in a short pamphlet (early 1799) the secession of 1798. After Fox's death he gave his support to Samuel Whitbread and the peace-at-any-price party.