As Mr Cameron sets about negotiating a new European Union arrangement better suited to the UK's needs and preferences, it is essential that he should understand something very important. It is that the renegotiated terms are not about detail; they are about principle.
From the leaks and speculation surrounding Mr Cameron's ongoing diplomacy the observer might think that they hinge on such questions as to whether immigrants should receive benefits, or whether the UK will be able to exercise some control over their numbers. These are details, details on which the ASI has differed with some in his party. We have taken the view that immigrants, especially skilled ones, should play an important part in the country's future prosperity.
They are still details, however, and if all Mr Cameron returns with is a ragbag of assorted concessions here and there, he will have passed up an historic opportunity for Britain. The principle at stake is sovereignty. It is whether the British people through their elected representatives can make the laws that prevail in this country.
Yes, of course the UK should remain part of the single market, and yes of course the goods and services we export to fellow members of the EU must meet EU regulations and conform to EU standards. The United States and China both meet those standards with goods they export there. But what we do not want is a European Parliament that passes laws telling us how to feed our dogs.
Britain needs to distance itself from "ever closer union" if it is to protect the liberties that are part of its inheritance from Magna Carta onwards. In most of the EU the laws tell people what they may do; in the UK the laws only tell us what they may not do. Britons do not derive their freedoms from Parliament. On the contrary, Parliament itself is a product of those freedoms.
Mt Cameron should remember that every concession on detail can be subsequently reversed. John Major's opt-out on the working hours directive was subsequently re-imposed upon us through EU health and safety provisions. What he must seek instead is a deal that recognizes the principle that our Parliament is sovereign in this country.
The hope must be that Mr Cameron will be able to negotiate a deal that puts Britain on the outside track of the EU, willingly going along with the economic aspects of union, but with UK sovereignty protected from those who seek a Europe governed in detail by Europe-wide laws.