Bahrain has always been since birth a Middle East anomaly. Unlike other Gulf states that emerged from British protection in 1971, Bahrain has practically no oil. It’s the Middle East’s smallest country with a land area the size of greater London. Without Saudi Arabian support, it would have gone bust decades ago and it is the only country in the world where a Shia majority is ruled by a Sunni dynasty.

But Bahrain seemed well-equipped to cope when the UK announced in 1967 that it would withdraw militarily from the Gulf. Oil had been discovered in 1932 and Arabia’s first refinery was opened on Sitra in 1941. It had Arabia’s first modern schools. Its airport was the first in the region to accept long-distance passenger aircraft. Gulf Air, the Arab world’s first airline, was founded in Bahrain in 1950. Bahrain at independence had a comprehensive health and education system. Bahrainis in 1971 were among the region’s healthiest, wealthiest and best-educated people.

The end of British protection also ushered in a new era of insecurity. In 1957, the Iranian parliament, citing that Persia’s conquest of the island 350 years earlier, had asserted the Bahrain formed Iran’s 14th province. How could Bahrain survive?

Its response was to seek confederation with Qatar and the seven emirates that now make up the UAE. Bahrain’s then ruler Sheikh Isa al-Khalifa was the first to call for a federation of lower Gulf emirates, but the nine-state federation foundered. Iran refused to tolerate Bahraini membership of a federation that Tehran believed would be dominated by the UK. Bahrain’s demand for a federal assembly elected on the basis of proportional representation, which would have resulted in Bahrain having almost half its seats, was rejected by the other eight.

On 14 August 1971, Shaikh Isa instead declared Bahrain’s independence. This created a fresh complication. Bahrain’s longstanding territorial dispute with Qatar would have been of little consequence if they had both been members of the same state. Once Bahrain opted to go it alone, the border with Qatar became an international frontier. To counter the likelihood that Manama would pre-emptively affirm its claims, Qatar decided to opt for independence in turn. The dream of a big Gulf federation, which today would have been one of the world’s richest nations, was irretrievably shattered.

The early year’s of independence were, nevertheless, highly productive. The oil price rises of 1973-74 boosted Bahrain’s economy. Bahrain became the region’s aviation, industrial and business hub. Gulf Air - then the flag-carrier of Abu Dhabi, Qatar and Oman, as well as Bahrain - dominated air routes to the Gulf. Bahrain’s international airport was the region’s busiest. Concorde flew to Manama from London until 1980. Aluminium Bahrain, the region’s first aluminium smelter, supported successful downstream industries. In 1976, Bahrain became an offshore banking centre.

Lower oil prices in 1976-78 exposed Bahrain’s economic fragility. The 1979 Iranian revolution inspired Bahrain’s Shia majority and provoked government repression. Plans were finalised for the construction of a causeway linking Saudi Arabia to Manama. Assertions that it was principally to promote trade were unconvincing.

The Iran-Iraq war dealt a further blow. Shipping companies shifted to Dubai, a more secure regional transshipment centre than Bahrain. Fearing Iranian subversion, police measures were intensified.

The 1990-91 Kuwait crisis and 2003 Iraq invasion were bad for the region, but good for Bahrain. It became a base for US and coalition forces. The Saudi Arabian causeway delivered tens of thousands of weekend visitors and served business people working in the kingdom who used Manama as a dormitory.

Rejecting confederation with Qatar and what is now the UAE was to have profound long-term economic consequences. But the most fateful decision made at independence was adopting, almost verbatim, Kuwait’s 1962 constitution which called for a sovereign, elected parliament. It was approved in 1973 and elections under a restricted franchise took place in December that year. The result was a parliament dominated by representatives of the Shia majority and fiercely republican Baathist and socialist MPs drawing support from Bahrain’s unionised industrial labour force.

Echoing steps taken by Kuwait’s rulers at the same time, Sheikh Isa dissolved parliament in August 1975 and made the dissolution indefinite the following year. The crushing of parliamentary democracy coupled with discrimination against Shia, which was mainly inspired by suspicions they were intractably disloyal, fed festering resentment.

It was successfully contained until the summer of 1994, when protests began in Shia villages and lasted for five years. They only ended after Sheikh Hamad succeeded his father as Bahrain’s ruler in March 1999 and promised a fresh start. A constitution similar to the 1973 document was approved by referendum in 2001, but the constitution implemented by decree on 14 February 2002 was fundamentally different to the form of constitutional monarchy that had been pledged.

Shaikh Hamad’s status was changed from emir to king. But there were two legislative chambers not one, and the elected house was balanced by a consultative council with equal rights comprising members appointed by the king, who was given the right to rule by decree. Opposition parties boycotted the first parliamentary elections in 2002 and in 2006. There was fuller participation in the elections of 2010 from which Islamist parties emerged with a majority. But frustration was building about the king’s failure to fulfil promises made in 2001. They exploded in February, when militants, inspired by the deposition of former Egyptian president Hosni Mubarak, took to the streets.

The arrival of Saudi Arabian troops on 14 March is in many ways the consequence of choices made 40 years before. Independence was not the first option, but fear of Iran and rivalry with Qatar led Bahrain to go it alone and depend upon Saudi Arabia. The rush to independence in 1971 led to the adoption of a constitution that would have resulted in the electoral deposition of the ruling family and rule by a resentful Shi majority, seen by Arabia’s rulers as vectors for Iran’s regional ambitions. Bahrain was trapped from the start between embracing Saudi Arabian dominance and giving way to their opponents. It was a balancing act that has finally come to an end.

From Riyadh’s perspective, Bahrain’s discordant independence was tolerable so long as there was no risk of the passions unleashed 40 years ago being transmitted to the Arabian mainland. Events in Egypt and the Bahrain government’s incompetent response to the protest movement convinced King Abdullah that waiting to see what happened next was unacceptably risky. The US, it seems, agreed.

There is an irony in the notion that Bahrain may have become the 14th province of Saudi Arabia, not of Iran, its restless Shia majority now part of the kingdom’s unhappy Shia minority. But the fact is that the constitution of 2002 has been suspended and may not be quickly restored. The people of Bahrain of all sects will probably experience for the foreseeable future the glacial pace of political evolution to which their Saudi counterparts have become accustomed.

This is a pity more than a tragedy. There are, as the citizens of Iraq can testify, worse fates in the today’s Gulf. And if there is any comfort for the Bahrainis who defied bullets, truncheons and tear gas this spring, it is that it is one that will be shared with no greater enthusiasm by all their compatriots.