Why does the British Government devote so much time and effort to cultivating the rulers of Bahrain, a tiny state notorious for imprisoning and torturing its critics? It is doing so when a Bahraini court is about to sentence the country’s leading human rights advocate, Nabeel Rajab, who has been held in isolation in a filthy cell full of ants and cockroaches, to as much as 15 years in prison for sending tweets criticising torture in Bahrain and the Saudi bombardment of Yemen.

Yet it has just been announced that Prince Charles and Camilla, Duchess of Cornwall, are to make an official visit to Bahrain in November with the purpose of improving relations with Britain. It is not as though Bahrain has been short of senior British visitors of late, with the International Trade Minister Liam Fox going there earlier in September to meet the Crown Prince, Prime Minister and commerce minister. And, if this was not enough, in the last few days the Foreign Office Minister of State for Europe, Sir Alan Duncan, found it necessary to pay a visit to Bahrain where he met King Hamad bin Isa al-Khalifa and the interior minister, Sheikh Rashid al-Khalifa, whose ministry is accused of being responsible for some of the worst human rights abuses on the island since the Arab Spring protests there were crushed in 2011 with the assistance of Saudi troops.

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Quite why Sir Alan, who might be thought to have enough on his plate in dealing with his area of responsibility in Europe in the era of Brexit, should find it necessary to visit Bahrain remains something of mystery. Sayed Ahmed Alwadei, director of advocacy at the Bahrain Institute for Rights and Democracy, asks: “Why is Alan Duncan in Bahrain? He has no reasonable business being there as Minister of State for Europe” But Sir Alan does have a long record of befriending the Gulf monarchies, informing a journalist in July that Saudi Arabia “is not a dictatorship”.

The flurry of high level visits to Bahrain comes as Rajab, the president of the Bahrain Centre for Human Rights, awaits sentencing on next week on three charges stemming from his use of social media. These relates to Rajab tweeting and retweeting about torture in Bahrain’s Jau prison and the humanitarian crisis caused by Saudi-led bombing in Yemen. After he published an essay entitled “Letter From a Bahrain Jail” in the The New York Times a month ago, he was charged with publishing “false news and statements and malicious rumours that undermines the prestige of the kingdom”.

This “prestige” has taken a battering since 2011 when pro-democracy protesters, largely belonging to the Shia majority on the island, were savagely repressed by the security forces. Ever since, the Sunni monarchy has done everything to secure and reinforce its power, not hesitating to inflame Sunni-Shia tensions by stripping the country’s most popular Shia cleric, Sheikh Isa Qassim, of his citizenship on the grounds that he was serving the interests of a foreign power.

Repression has escalated since May with the suspension of the main Shia opposition party, al-Wifaq, and an extension to the prison sentence of its leader, Sheikh Ali Salman. The al-Khalifa dynasty presumably calculates that US and British objections to this clampdown are purely for the record and can safely be disregarded. The former Foreign Secretary Philip Hammond claimed unblushingly earlier this year that Bahrain was “travelling in the right direction” when it came to human rights and political reform. Evidently, this masquerade of concern for the rights of the majority in Bahrain is now being discarded, as indicated by the plethora of visits.

There are reasons which have nothing to do with human rights motivating the British Government, such as the recent agreement to expand a British naval base on the island with the expansion being paid for by Bahrain. In its evidence to the Select Committee on Foreign Affairs, the Government said that UK naval facilities on the island give “the Royal Navy the ability to operate not only in the Gulf but well beyond in the Red Sea, Gulf of Aden and North West Indian Ocean”. Another expert witness claimed that for Britain “the kingdom is a substitute for an aircraft carrier permanently stationed in the Gulf”.

10 examples of Saudi Arabia's human rights abuses Show all 10 1 / 10 10 examples of Saudi Arabia's human rights abuses 10 examples of Saudi Arabia's human rights abuses In October 2014, three lawyers, Dr Abdulrahman al-Subaihi, Bander al-Nogaithan and Abdulrahman al-Rumaih , were sentenced to up to eight years in prison for using Twitter to criticize the Ministry of Justice. AFP/Getty Images 10 examples of Saudi Arabia's human rights abuses In March 2015, Yemen’s Sunni President Abd-Rabbu Mansour Hadi was forced into exile after a Shia-led insurgency. A Saudi Arabia-led coalition has responded with air strikes in order to reinstate Mr Hadi. It has since been accused of committing war crimes in the country. Getty Images 10 examples of Saudi Arabia's human rights abuses Women who supported the Women2Drive campaign, launched in 2011 to challenge the ban on women driving vehicles, faced harassment and intimidation by the authorities. The government warned that women drivers would face arrest. Getty Images 10 examples of Saudi Arabia's human rights abuses Members of the Kingdom’s Shia minority, most of whom live in the oil-rich Eastern Province, continue to face discrimination that limits their access to government services and employment. Activists have received death sentences or long prison terms for their alleged participation in protests in 2011 and 2012. Getty Images 10 examples of Saudi Arabia's human rights abuses All public gatherings are prohibited under an order issued by the Interior Ministry in 2011. Those defy the ban face arrest, prosecution and imprisonment on charges such as “inciting people against the authorities”. Getty Images 10 examples of Saudi Arabia's human rights abuses In March 2014, the Interior Ministry stated that authorities had deported over 370,000 foreign migrants and that 18,000 others were in detention. Thousands of workers were returned to Somalia and other states where they were at risk of human rights abuses, with large numbers also returned to Yemen, in order to open more jobs to Saudi Arabians. Many migrants reported that prior to their deportation they had been packed into overcrowded makeshift detention facilities where they received little food and water and were abused by guards. Getty Images 10 examples of Saudi Arabia's human rights abuses The Saudi Arabian authorities continue to deny access to independent human rights organisations like Amnesty International, and they have been known to take punitive action, including through the courts, against activists and family members of victims who contact Amnesty. Getty Images 10 examples of Saudi Arabia's human rights abuses Raif Badawi was sentenced to 1000 lashes and 10 years in prison for using his liberal blog to criticise Saudi Arabia’s clerics. He has already received 50 lashes, which have reportedly left him in poor health. Carsten Koall/Getty Images 10 examples of Saudi Arabia's human rights abuses Dawood al-Marhoon was arrested aged 17 for participating in an anti-government protest. After refusing to spy on his fellow protestors, he was tortured and forced to sign a blank document that would later contain his ‘confession’. At Dawood’s trial, the prosecution requested death by crucifixion while refusing him a lawyer. Getty Images 10 examples of Saudi Arabia's human rights abuses Ali Mohammed al-Nimr was arrested in 2012 aged either 16 or 17 for participating in protests during the Arab spring. His sentence includes beheading and crucifixion. The international community has spoken out against the punishment and has called on Saudi Arabia to stop. He is the nephew of a prominent government dissident. Getty

These dreams of restored naval might are probably unrealistic, though British politicians may be particularly susceptible to them at the moment, imagining that Britain can rebalance itself politically and economically post-Brexit by closer relations with old semi-dependent allies such as the Gulf monarchies. These rulers ultimately depend on US and British support to stay in power, however many arms they buy. Bahrain matters more than it looks because it is under strong Saudi influence and what pleases its al-Khalifa rulers pleases the House of Saud.

But in kowtowing so abjectly to Saudi Arabia and the Gulf kingdoms, Britain may be betting on a flagging horse at the wrong moment. Britain, France and – with increasing misgivings – the US have gone along since 2011 with the Gulf state policy of regime change in Libya and Syria. Saudi Arabia and Qatar, in combination with Turkey, have provided crucial support for the armed opposition to Bashar al-Assad. Foreign envoys seeking to end the Syrian war since 2011 were struck by British and French adherence to the Saudi position, even though it meant a continuance of the war which has destabilised the region and to a mass exodus of refugees heading for Western Europe.

Whatever the Saudis and Gulf monarchies thought they were doing in Syria, it has not worked. They have been sawing off the branch on which they are sitting by spreading chaos and directly or indirectly supporting the rise of al-Qaeda-type organisations like Isis and al-Nusra. Likewise in their rivalry with Iran and the Shia powers, the Sunni monarchies are on the back foot, having escalated a ferocious war in Yemen which they are failing to win.

In the past week Saudi Arabia has suffered two setbacks that are as serious as any of these others: on Wednesday the US Congress voted overwhelmingly to override a presidential veto enabling the families of 9/11 victims to sue Saudi Arabia. In terms of US public opinion, the Saudi rulers are at last paying a price for their role in spreading Sunni extremism and for the bombing of Yemen. The Saudi brand is becoming toxic in the US as politicians respond to a pervasive belief among voters that there is Saudi complicity in the spread of terrorism and war.