History, even British political History, is full of fine ideas that didn't quite work out in practice. The Party of Peel and Disraeli became that of Johnson and Truss; the party of Gladstone and Lloyd George became that of Clegg and Davey; the party of Keir Hardie became that of Keir Starmer. By a miraculous reversion of this process of moral entropy, the Prevent programme has been exalted from