The new century witnessed the deaths of a whole leadership generation: Jones of Nayland in 1800, Boucher in 1804, Horsley in 1806, William Stevens early in 1807.

Horsley was in fine form during the 1806 Parliamentary summer session, savaging the slave trade with characteristic vigour on 24th June. In September, arriving in Brighton to visit Lord Thurlow, he found his old friend and patron dead. Two weeks later Horsley himself became fatally ill. Although Trafalgar had inspired him to preach exultantly of victory, on his deathbed he despaired of the bloody and protracted struggle to break Napoleon's grip on continental Europe.

Horsley's death was an irreparable loss to the group. No figure of comparable stature emerged among High Churchmen until the Oxford Movement; Van Mildert, later forced by pressure of events into something of the same rôle, could never match his master's breadth of intellectual sympathy and oratorical brilliance. Horsleyisms became part of the Lords' stock-in-trade, quoted in debate by all sides far into the new century; but Horsley himself was gone, depriving the High Church reform movement of its figurehead and statesman. Piloting schemes for the renewal of the Established Church past Radical hostility on one side and deeply suspicious High Tory peers on the other, when the political atmosphere tainted all reform measures with danger to the established order, was a task for a master. Horsley might have attempted it; without his leadership, the main current of High Church reforming activity was forced into extra-parliamentary channels.