Fortunately, however, Castlereagh had a rhinocerine hide for criticism; Salisbury commended him for his contempt for "whipper-in statesmanship" and the way he made "petty parliamentary tactics appear infinitely despicable". On walking down to Parliament with the (almost equally hated) Home Secretary Lord Sidmouth and encountering a mob, Sidmouth said: "Here we go, the two most popular men in England." "Yes," replied Castlereagh, "through a grateful and admiring multitude." He added that it was more "gentlemanly" to be disliked by the mob than liked by them, which was some compensation for their habit of constantly smashing the windows of his London house.

Bew's diligence in 13 archives in several countries and deep reading in the literature of the day — no fewer than 37 contemporary newspaper publications are cited in the notes — has produced a scholarly defence of this great Tory paladin. Personally incorrupt, Castlereagh had a fine eye for appointing the right man to the right job: Richard Wellesley was given the governor-generalship of India on his recommendation, for example, and consolidated British rule there with the help of his brother Arthur, later Duke of Wellington.

Although the Liverpool government's repressive measures after Waterloo — particularly the Peterloo Massacre and the Six Acts of 1819 — were not solely Castlereagh's doing, as leader of the Commons he represented their public face, and they gave the opposition the perfect opportunity to blacken the reputation of someone they had loathed for a quarter of a century. Castlereagh personally hated having to impose dictatorial laws that Napoleon himself had used, but as Salisbury later pointed out there is in politics a "just Nemesis which generally decrees that partisans shall be forced to do in office precisely that which they most loudly decried in opposition". Bew makes a good case for Castlereagh's support for law and order and his opposition to mob rule, which is a convincing one and in light of the Hobbesian descent into mayhem and tragedy on British streets in August will hopefully strike a chord with readers.

Bew also questions Douglas Hurd's admiration for Castlereagh. He believes Hurd pictured Castlereagh as a do-nothing realist. But as Bew points out, Castlereagh — with the exception of a brief period in 1802-3 when he half-heartedly defended the Peace of Amiens — "was one of the most unremitting exponents of the view that no deal could be negotiated with Napoleon and that he must be fought to the end. To that end, both he and Canning were prepared to take daring, unilateral and pre-emptive action, without the sanction of other allies — the bombardment of Copenhagen being the most infamous example." Also, "If Castlereagh is to be regarded as the British Foreign Secretary who cooperated more effectively with the Continental powers than any other, this should come with the concomitant recognition acknowledging that he was also the War Secretary who created the biggest British army in history to that point, precisely so that it could operate on European soil." Bew also states: "In Castlereagh's career, negotiation was never confused with appeasement and he recognised that talking sometimes had its limits, such as from 1812 to 1815, before the Congress system took shape, when he was unwilling to countenance appeasement of Napoleonic France or Tsarist Russia. ‘It was a measure not of war but preventative of war,' Charles Stewart later wrote of his brother's refusal to bend to Russia over the issue of Poland." Bew concludes: "Viewed in this way, the echoes of Castlereagh's career perhaps evoke different historical analogies than those which Hurd, or others, have considered."