The disappearance and suspected murder of journalist Jamal Khashoggi at the Saudi consulate in Istanbul is the latest in a long line of reasons for questioning Britain's relationship with Saudi Arabia and the other Gulf monarchies.
It's a relationship that has never been viewed with much enthusiasm by the British public nor, indeed, by large sections of the media but it is one that successive British governments, both Labour and Conservative, have gone to extraordinary lengths to protect.
The strength – and apparent warmth – of the relationship at government level is in some ways puzzling. Britain, as a society, has little in common with these repressive Gulf states, and yet its government remains nervous about criticising them openly even when there are obvious grounds for doing so.
The explanation for this attitude is what London University researcher David Wearing describes as "a unique combination of economic and strategic ties". In a timely new book, "AngloArabia: Why Gulf Wealth Matters to Britain", he explores the nature of these ties and why they are so important today.
The popular idea, of course, is that it's "all about oil", and oil is certainly a central factor, though not quite in the way that is often imagined. Wearing points out – perhaps surprisingly for many readers – that Britain doesn't actually depend heavily on the Gulf for its oil supplies. It does, however, have commercial interests in the Gulf's energy industry and, more crucially, large parts of the Gulf states' oil revenues are recycled back to Britain in the form of investments or arms purchases.
The Gulf is a growing market and, partly as a result of arms sales, Britain has a trade surplus with the region. Its exports to the Gulf, worth around £14 billion a year, are roughly on a par with exports to China and India combined.
Britain has also received substantial share of investment as Gulf states seek to diversify their economies. Gulf states have been investing heavily in infrastructure at home too – which creates further opportunities for British companies. Wearing quotes Foreign Office minister Lord Howell, speaking in 2012: "In infrastructure alone there are plans to invest an estimated $2 trillion over the next decade. Here in Britain we are striving to be the Gulf's commercial partner of choice."
British arms sales to Saudi Arabia have become especially contentious in the light of the kingdom's disastrous military intervention in Yemen and are of questionable legality. But attempts in parliament to suspend them pending further investigation of alleged war crimes have been repeatedly blocked, sometimes by devious means.
Wearing points out that these arms sales are not just about money or providing jobs in Britain: "They play a vital role in sustaining the UK's arms industry, which in turn is indispensable to maintaining Britain's status as a global military power."
The other side of this equation is that British weapons have helped to preserve monarchical rule in the Gulf. The political consequences of that are mostly beyond the scope of Wearing's book but he views arms exports as "one component of a broader system of military cooperation aimed at ensuring the survival of the conservative regional order".
It would be a step too far, he suggests, to claim that without British support the Gulf states would now be models of democracy, since there are other factors involved. Even so, he says, "Britain has consistently provided material support to the autocratic rulers of the Gulf, including arms and training for internal security forces with an extensive record of human rights violations, such as the violent suppression of democratic activists and movements. It has been a significant external provider of these forms of assistance to all the Gulf Arab monarchies from their creation ..."
Wearing also questions British governments' habit of soft-pedalling on rights abuses in the Gulf, arguing that there is more scope for manoeuvre than they claim. The relationship, he says, is one of "asymmetric interdependence": while Britain and the Gulf depend on each other, it is Britain that holds the stronger position. In practical terms, he says, the GCC states rely on the UK, and to a far greater extent on the US, for their defence and – ultimately – their survival.
The implication is that Britain has the scope, if it chose, to become more judicious in its dealings with the Gulf. As present, though, it appears to be moving in the opposite direction. Following the Brexit vote, we now have a situation where the British government is seeking to strengthen ties with the Gulf as it loosens those with its European neighbours.
The political rhetoric surrounding this is increasingly absurd. While the EU is characterised as a dictatorship, the real dictators in the Gulf are characterised as friends. Last week, for instance, in the midst of the Khashoggi affair, foreign secretary Jeremy Hunt spoke of Britain's "shared values" with Saudi Arabia – in contrast, presumably, to the nasty EU which his predecessor, Boris Johnson, has described as pursuing similar goals to Adolf Hitler.