It is rare that a visit by a foreign leader goes wrong; more likely, if there is acrimony, that it just doesn’t happen. But the visit of King Abdullah of Saudi Arabia has been complicated by his own pre-emptive criticism of Britain’s efforts against terrorism, and the unforeseen absence, for personal reasons, of David Miliband, the Foreign Secretary.

Those are just prickles on the surface of a relationship that is uncomfortable for more profound reasons. During this visit, there will be real disagreement about the Middle East peace summit supposed to happen in the US next month. There will be public protests against the kingdom’s abysmal human rights record. Over it all hangs the shadow of the al-Yamamah arms deal. Tony Blair halted a Serious Fraud Office investigation into the deal between BAE Systems, the defence contractor, and Saudi Arabia in the interests, the Government said, of the necessary relationship with the kingdom, but the US, far more exercised on the principle of propriety in such contracts, is likely to be tenacious.

There are plenty of cases where a government is justified in saying that it chooses to set aside unattractive aspects of its guests to pursue other goals. In Saudi Arabia, Britain has one good reason: the need for stability in the region. But it has one bad one: the web of commercial ties, which it has appeared too willing to put above ethical concerns, and which, if corrupt, do nothing to help to nudge the kingdom in the direction that Britain says it wants.

Of all the difficulties, it is worth leaving David Miliband out of it. The Foreign Secretary’s sudden cancellation of the meeting, explained by his and his wife’s adoption of a second child, should be taken at face value, for all the conspiracy theories that promptly whirled around.

There is no question that it might have been better handled; surely a substitute of equivalent status could have been found, instead of Kim Howells, a fluent but junior minister? Jack Straw, who as Foreign Secretary was entirely familiar with the issues and pitfalls? Des Browne, Defence Secretary? But even if Mr Miliband’s reason seemed novel, even improbable, to the guests, it is worth respecting, given the blowtorch of attention that was turned on the couple’s first adoption.

It would take more generosity to step around the King’s attack on Britain’s use of counter-terrorism intelligence. It was unhelpful, but all the same, this is a minor dispute, running since the 2005 suicide bombings in London. The Saudis say that Britain failed to use the intelligence they provided; Britain says it was too vague.

But on the arguments of real substance, there is likely to be no progress.

Saudi Arabia has a long list of demands for its participation in the proposed Middle East summit in Annapolis (which may yet slip to December, or not happen at all). Its presence would bring in other Arab countries, and give the gathering credibility. Those demands were never going to be met in full. But Britain has the unenviable role, at the US’s urging, of trying to sound out a compromise. This looks harder by the day as Israel cuts fuel supplies to the Gaza Strip.

The human rights questions are beyond dispute. They represent irreconcilable views of the relation between leaders and the people. The boycott by Vince Cable, even if merely leader of Britain’s third-largest party, will sting.

Compromises are necessary in diplomatic relationships. But it would be easier for Britain to justify the Saudi ones if it could argue that it was persuading the kingdom to reform. The concern about past arms deals is that they consolidated the old aspects, not the new.

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