The deal was so advantageous to those two original members that General de Gaulle was determined to make it stick and therefore vetoed Britain's belated application to join until it had been concreted into place. Much of my early time as a British diplomat was spent in trying to circumvent that Gaullist veto.
The result was always going to be a disaster for Britain, as I could see by virtue of my birds-eye view from, first, the Foreign Office and then the British Embassy in Brussels.
Instead of a rational trading pattern in which they imported efficiently produced food and raw materials from countries that offered them in return for preferential treatment for British manufacturers, the British taxpayer was required to subsidise inefficient French agriculture and then to pay again as a consumer by way of higher food prices - thereby negating Britain's one major cost advantage as a manufacturing economy - while British manufacturers lost their preferential markets and had to compete in the same market as powerful and efficient German producers.
The outcomes were inevitable, although ignored by those enthusiasts for whom "Europe" had become the promised land. The British "trade gap" widened alarmingly, British manufacturing was decimated, the British taxpayer continued to pay large sums into the EU coffers, and Britain's links with its traditional trading partners were weakened.
These burdens bore most heavily on working people who found, in addition, that their employment prospects, available housing, and public services were greatly reduced and weakened by the influx of migrants from eastern Europe who were keen to exercise their right as EU citizens to settle in the UK.
The outcome of the referendum should not really, therefore, have come as a surprise - but it did. The bien-pensants - those who "know best" - were greatly attached to the notion of a Europe that carried with it a kind of cultural cachet, and they were remarkably insouciant about the price that was being paid.
They were reluctant to accept the result of the referendum which they attributed to the "ignorance" and "racism" of those who "didn't really understand" what a wonderful ideal "Europe" (which they conflated with the particular arrangement known as the European Union) really was.
They therefore set about doing all they could to reverse the result, through a sustained campaign (particularly in the pages of the Guardian, which gave up all pretence of impartiality on the issue) to hold a second referendum in which the "mistake" could be rectified.
In doing so, they gave of course great comfort to the EU bureaucracy which was encouraged to believe Brexit wouldn't really happen.
That bureaucracy of course had its own agenda. They were terrified that other countries - like Greece and Spain, even now Italy - that had suffered terribly as a result of the undemocratic and banker-driven intransigence of EU rules and institutions, might also want to leave. They determined therefore to show other backsliders that exit was not an easy option.
The result? The "Europe" held up as the key to a wonderful future proved to be remarkably impervious to the ideal of unity and more concerned with protecting its own structures and institutions than with building a co-operative arrangement with a departing Britain.
The combination of a misguided rearguard action at home and a determination in Brussels to punish the British for their temerity in leaving has made the negotiation of a sensible arrangement almost impossible.
If these problems are to be overcome, the answers are to be found at least as much in Brussels as in Westminster and Whitehall. Those with hearts and minds that are big enough could take the Brexit talks as an opportunity to build a new "Europe" that could fix its many current failings by becoming more democratic and less wedded to the neo-liberal prescriptions of its central banks and bureaucracies.
But, on the evidence so far, sadly, that seems unlikely and a goal that had seemed so inspiring looks certain to become mired in its own short-sightedness.
