What with his love of tarantulas and his eye for the political stunt, Britain’s nakedly ambitious Defence Secretary, Gavin Williamson, is in some danger of becoming a figure of fun. Russia should just “go away and shut up”, he recently told Policy Exchange in response to the Salisbury nerve agent attacks. Is it possible to take such a politician seriously?

The military had better hope that it is, for not in a very long time have its commanders encountered a Defence Secretary who better understands and promotes the urgent need for more spending and, perhaps more important still, root and branch modernisation and reform of the way the budget is spent.

He has already made some progress, persuading...