The first manifesto commitment had been entered into in 2008, an understated, even ethereal, threat that if Lisbon were ratified by the present government, Conservatives ‘would not let matters rest there’. While intended as a policy sticking plaster, as the EU rose back up the political agenda this commitment moved to centre stage.

A second crucial element was a clear cut pledge to restore the Social Chapter opt out, which by definition meant that a renegotiation of the treaties was on the cards.

Much to their surprise, the new Government found that, in an ionised political atmosphere, these commitments began to build their own momentum, carrying it forward to contemplate a more fundamental realignment in ways that even a year earlier it would have thought unimaginable.

The red button was a promise made in late 2009 that had appeared to be little more than a sensible accounting exercise. It was a pledge on entering office just to do the sums. Treasury officials would be quietly instructed within the first week of the new government to begin a cost-benefit analysis of EU membership.

The concept had long been highly controversial. On at least two occasions, previous Chancellors had quashed research looking into the figures. Both Ken Clarke and Gordon Brown had pulled the plug on the suspicion that the figures likely to emerge were going to be embarrassing; in Chancellor Brown’s case, the analysis was pooh- poohed as a stunt by relatively junior staff on their own initiative.

Treasury staff were tasked with coming up with the basic audit: net and gross budget contributions; cost of red tape; impact on trade with EU member states; tariff barriers with the rest of the world; projected emerging markets, and so on. Other government departments were invited to contribute to the more broad brush aspects in areas relating to them. Civil servants took to the task with fascination and aplomb.

The five pages contributed by the Leader of the House were the most contentious, dealing with the abstracts of democracy and accountability, though the Home Secretary’s chapter also sparked some Cabinet controversy in the civil liberties paragraphs.

In any event, the Treasury officials beavered away over the late spring. The initial figures quickly leaked, hardly surprising given the sums involved. The early working draft revealed that there was a division of opinion. One group of civil servants took a laser beam view and held that EU membership cost the UK four per cent of its GDP every year in fees and bills. A second group, however, held that this figure did not reflect accurately the subsidiary and more widespread damaging effects of membership, and held the true figure to run at between 8 and 9 per cent.

The British press were staggered; ‘Mugged!’ bellowed the front page of The Sun. The continental press in turn took a particular interest when the figures across the EU as a whole were released. This was originally intended to be kept from the final document for reasons of diplomatic nicety. They ran at €1,219 billion per year. With 500 million EU citizens, that cost an average of nearly €2,500 per EU citizen every year.

Attempts to rubbish the statistics were blown out of the water by former European Commissioner Gunther Verheugen, who was interviewed in bronzed beachfront retirement and restated his former claim that EU red tape alone cost businesses €600 billion, or around a twentieth of the whole EU economy.

The conservative Treasury estimate now looked excessively cautious, and consensus settled at a cost to the UK (depending upon the Pound/Euro exchange rate) running in the order of between £117 billion and £134 billion per year.

Against this, the benefits looked weak. This was because there remained considerable uncertainty as to what tariff and non-tariff barriers UK exporters would face if the country were not a member. The Department of Business had already for some time assessed that even outside of the EU, the UK would still enjoy preferential access. In the worst case scenario this would be the ‘most favoured nation tariff’, a misnomer, as this provided for no preferential tariff, though in turn it would itself encourage the UK and EU exporters as well,to establish a free trade agreement.

The wild card was over non-tariff barriers, particularly differences in regulations, such as Health and Safety rules. The best case scenario was initially viewed as a deal permitting full continuing access to the Single Market similar to that of members of the European Free Trade Area (EFTA), though without influencing the legislation that governed it.

On review, however, that position was struck out as too much a legacy of an old political holding line, designed to distract MPs from possible alternatives. New choices were explored; a bilateral trading agreement, such as that between the EU and Canada or Mexico, which were ‘EEC Treaty Lite’; reinvigorating and expanding EFTA, and re-establishing a broader bilateral deal; or adopting a unilateral quid pro quo arrangement so that if legislation hampered UK exports, similar levels of bureaucracy would be placed on EU imports until the situation was fixed.

There were as a result several possible costings as to how trade would be affected in the new post-EU world. The one thing that officials agreed on was that in each case, developing WTO rules had made international trade a very different proposition from the time of the UK’s accession to the EEC. World tariff levels had plummeted, so the physical trade benefits of membership had diminished considerably and were outmatched by the costs. The sums that had encouraged joining the EEC in the 1960s and 1970s and which until 1976 had still seemed to justify the decision, now clearly produced a result in the opposite direction.

The officials tallied the costs with the benefits that couldn’t be achieved with a bilateral arrangement. They came up with the bill for the political project of building a country called Europe.

All told, membership cost Britain around £100 billion more than it brought in, nine tenths of which were due to the bureaucracy. The remainder came straight out of the till every year.

Britain was paying a premium to belong to a gym whose other members beat it up.

It now became clear why such a report had previously been quashed. Journalists went mental. MPs were outraged. Tax payers were flabbergasted. The call had already gone out for a new Fontainebleau deal. Many started to demand something far more radical; a couple of billion in rebate this time was not going to wash.