David Cameron and Ed Miliband are stuck in an abusive relationship which will only end when one or other of them is forced to move out. In 12 weeks’ time, the voters will have the opportunity to decide which of the two that is going to be. But meanwhile, every time the couple meet, they cannot stop competing to see who can utter the most demeaning insults.

Today we had Miliband declaring: “He’s a dodgy Prime Minister surrounded by dodgy donors.” And we had Cameron responding by taking aim at Miliband and Ed Balls: “Those two in the Treasury were the friends of the tax dodger.”

Miliband feels compelled to say this sort of thing, in order to demonstrate that he has not been crushed by the Prime Minister. And Cameron feels compelled to answer in kind: to be if possible even more scornful of his opponent than his opponent has been of him.

The Labour leader adopts a tone of solemn outrage. Cameron does the same, but also has a not entirely attractive propensity to allow a gleam of amusement, even of triumph, to cross his face when he thinks he has said something particularly witty at his opponent’s expense. So although people are unlikely to think more highly of Miliband after today’s exchanges, they are also unlikely to think more fondly of Cameron.

No wonder the audience for these encounters is diminishing. The Chamber is less full, and even the greatest fans of PMQs look forward to it with less eagerness than has often been the case in the past. For the backbenchers reinforce their leaders’ weaknesses: on the Labour side, they mostly asked about tax evasion, while on the Conservative side, they boasted about growing employment in their constituencies, which is attributed to good old Oltep (Our Long-Term Economic Plan).

The effect of this almost unbearable level of repetition is to make the Commons seem parochial. Free men and women devote years of their lives to get elected to this great deliberative assembly, in order to ask almost identical questions which have been written for them by other people.

Sir Peter Tapsell, Father of the House, showed, as he did three weeks ago, that it is possible to think for oneself, and to range far beyond the parochial topics on which electoral strategists insist. Sir Peter declared that “while Ukraine is of absolutely no strategic importance to Britain, Greece most certainly is”. And he warned that “unless western statesmen show rather greater skills than they have in recent years, Greece is going to pass into the Russian sphere of influence without a shot being fired”.

While this timely warning was being uttered, Philip Hammond, the Foreign Secretary, sat with a supercilious smile on his face, as if to say that he and his fellow functionaries have long ago thought of that. But even if they have, it is not at all clear that they have the faintest idea what to do about it.