Mr Allister did not benefit from the land sale in question and the DUP later said that people were free to sell property to who ever they wished. No mention of newspapers, cars or computers – just property. (In fairness, Mr Robinson did not suggest that unionists should sell poor land to republicans at inflated prices. Presumably, intolerance trumps enterprise.) So, you say, that is the end of it. Well, not really. Calls for Mr Robinson to apologise missed the point. The first minister’s behaviour is symptomatic of a long-standing illness in our society. Demanding an apology is a bit like trying to scrub off the spots associated with measles – even if you managed to remove them, the illness would still be there. (In Mr Robinson’s case, the spots are still there too.) So what exactly is this illness and how might we cure it? It is a disease caused by three viruses. The first is political arrogance.

Mr Allister asked the first minister a perfectly reasonable question: What will happen to the £18 million earmarked for the now shelved Maze peace centre?

Mr Robinson might have been expected to reply that officials were working on it, or some equally standard answer.

Instead he attacked Mr Allister personally. (Mr Robinson may deny that this is how his response should be interpreted but since he refuses to grant an interview to this newspaper, we shall be denied the pleasure of an explanation.) Hence the political arrogance: our first minister does not feel obliged to answer questions in the assembly. Why should he? There is no opposition to hold him accountable and, as a result, we still have no idea what will become of the £18 million.

Despite the absence of an opposition, it might be assumed that the speaker would have acted in Mr Allister’s defence, by pointing out that allegations (which were untrue) about an MlA’s personal finances were irrelevant to the question. Instead the speaker, Willie Hay of the DUP, chastised Mr Allister for shouting. He later said that during the exchanges, no law had been broken – an opinion which allowed Mr Robinson’s remarks to stand. (Mr Hay might learn the difference between law and ethics. If he needs tuition on the matter, Mr Allister is exceptionally well qualified to help.)

The second virus is naked sectarianism. Behind the mask of parliamentary procedure, power sharing and smiling ministerial faces across the world, stormont is built on sectarianism and cannot operate without it. Power-sharing on a sectarian basis merely gives power to the most sectarian. The system works, in that it stops both sides killing each other, but the price is that they are allowed to kill democracy and good government instead. The third virus is rampant political insanity. Does Mr Robinson believe that property should not transfer across all politico-religious boundaries or just some? Would it be acceptable for unionists to sell land to SDLP [Social Democratic and Labor Party] supporters? How about Catholics in general? (House for sale to good Protestant. Would consider lapsed Catholic for quick sale.)

How far does his theology of commerce extend? (Kitten available to good home. Free to Presbyterians, but not to Free Presbyterians.) His attitude is on a par with David Cameron telling Conservatives not to sell property to their fellow coalition partners, the liberal Democrats. (Wouldn’t you just hate it if Nick Clegg bought your house?) So we are ruled by a First Minister whose attitude suggests that business should be the religious service sector. (For sale: Methodist Ford Mondeo.) Perhaps inward investors should be scanned for traces of Catholicism and supermarkets should check customers’ religion. (Special offer on Protestant bread this week. Please show ID at check-out.) The assembly as a whole would be more tolerant – it would advocate separate shopping aisles for Catholics and Protestants in its usual yellow pack politics.

Mr Robinson’s behaviour is the inevitable outcome of 400 years of the Ulster disease. A non-sectarian society is the only known cure. Until then, his attitude should not surprise us. All he did was expand ‘not an inch’ into ‘not an acre’.