Is Theresa May putting party above country by keeping Boris Johnson as Foreign Secretary? The answer is yes. There can be no other reason he is still in post.

We all know why. If Boris were to be fired, he would turn nasty. First, he would secure himself a highly-paid column or two, just to tide him over the bad times and to give himself a bully pulpit. Then, behind the scenes, he would plot and scheme, drawing as many disaffected former ministers and passed-over backbenchers as possible into his orbit, with a view to launching a challenge that might, just possibly – who knows? – ­propel him into Downing Street. Either that or into the wilderness.

He may be Her Britannic Majesty’s Principal Secretary of State for Foreign and Commonwealth Affairs, but he really has no interest in the job, save for the prestige it confers and the platform it provides, as well, one imagines, as the chance to travel in style to exotic parts at the taxpayers’ expense.

From the PM’s point of view, it is the last of these perquisites that is the most important. Boris may make a fool of himself in distant parts, but at least while he’s abroad he’s not meddling at home.

The problem is that while he continues to exploit one of the great offices of state as merely a means to an end – his own aggrandisement – he is denying the United Kingdom a serious voice in world affairs.

Consider this selection of his most recent predecessors: Jim Callaghan, Douglas Hurd, David Owen, Malcolm Rifkind, Geoffrey Howe, Robin Cook, Margaret Beckett, David Miliband, William Hague. All serious men, plus one very serious woman. No one doubted that they put in the hours and did their utmost both to represent their country and to help preserve peace and order in the world.

Johnson is not a serious addition to their ranks. It is as if P.G.Wodehouse were to be placed next to James Joyce, Henry James and Aleksandr Solzhenitsyn at a literary dinner. But while  “Plum” would probably have proved a welcome distraction, not least to others round the table, “Boris” at international gatherings goes down like a lead balloon.

As a linguist, he’s a bluffer (and I should know). Speaking French during an interview in Paris during his time as London mayor, it was clear that he just about got the drift of the questions put to him, but could only bluster in response before reverting to English.

He claims to be able to read novels in French and Spanish, and perhaps, with a dictionary to hand, he can. But he is no linguist.

Last year, giving a joint press conference with the German foreign minister, Frank-Walter Steinmeier, the first thing Boris did was to pull on earphones in order to understand what Steinmeier was saying. He then indulged in a 15 seconds of mangled German, ending with a characteristic guffaw, before turning to the British press to ask: “How about that? Would you like me to translate that for you?”

In fairness, he made the effort. My point is that foreign languages much beyond basic GCE level are not really his thing. He pretends that the reverse is true because it plays to his idea of himself as an educated “liberal cosmopolitan” rather than what he is in fact – an upper-middle-class Englishman.

Of all the qualities most admired by the Romans – gravitas, pietas, dignitas and virtus – he has none of them. You don’t need to imagine Boris at Vienna or Versailles to realise that he is not the man for the hour.

Politically, we all have our views. Some of us are for Brexit, others are against. And so is Boris. Not long after the referendum, we discovered that he had written two columns for the Telegraph in which he outlined his position on Europe. In one, he spoke of the terrible constraints imposed on Britain by the EU; in the other he lauded them. As he waited to see which way the wind was blowing, he had two cakes prepared, both made from his own words, one for eating, the other for the June 23rd bakeoff.

Since then, as foreign secretary, he has blundered his way across the world stage, irritating or confusing the leaders he encounters. Hardly ever does he say anything of substance. More often than not he says nothing or utters only clichés. On Europe, he promises a brilliant future for Britain in the global economy, but never explains how this is to be achieved. At the same time, he warns our erstwhile European partners in the midst of difficult negotiations that they can “whistle” for any alimony due them post-Brexit.

It will be recalled that he joked in the Spectator that President Erdogan of Turkey was a “wanker” who liked to have sex with goats. That at least was before he rejoined the Cabinet. More recently, he said it was no bad thing that President Assad, with help from Russia, was winning the war in Syria. During last November’s U.S. elections, he likened Hillary Clinton to “a sadistic nurse in a mental hospital”. Donald Trump, who defeated Clinton, was subsequently – and perhaps more understandably – dismissed as someone he would not like to run into in a dark alley in New York. This year, worshippers in a Sikh Temple, bound by their faith to eschew alcohol, were told gleefully that he would be pushing to sell more “clinky” – scotch whisky – to India after it leaves the EU.

He is like a boisterous dog that needs to be confined to the conservatory when guests are present lest it is sick on the carpet or starts humping grandma’s leg.

So I ask again, why doesn’t the PM get rid of him and appoint someone who knows what they are doing to one of the most important jobs in government? As we look ahead to an independent future, we need our top diplomat to be a skilled negotiator, ready to make new friends and allies, not a tub-thumper driven by nothing beyond personal ambition. If thwarted, Boris’s potential to make mischief within Conservative ranks is considerable – though how effective he would be is another matter. But wouldn’t it be better if that mischief was confined to the Tory party, where it belongs, and not stretched out across Europe and the world?

As for the plight of Boris in a future in which he is is denied the opportunity to wreak havoc in Number 10, surely we need not concern ourselves overmuch. There are plenty of editors and publishers out there ready to throw money at the man who, since the death of Bruce Forsyth, they are calling Mr Entertainment. He could make a small fortune, maybe even a large one, from newspapers, books and television – half a million pounds at least for his memoirs, more if he includes details of his many romantic excursions.

It was another Johnson who said that no one (other than Donald Trump, Philip Green and thousands of others) is more innocently engaged than when making money. It is time to put the good doctor’s theory to the ultimate test. Theresa May must give Boris the chance to prove his innocence.