The UK government should say something like this:
“In 1972 the Uk joined the EEC. This was known as the Common market in the UK. In 1975 the then Labour government gave the UK public a referendum on whether they should remain in the EEC. The whole scheme was clearly defined by the leading politicians in favour as simply a common market that would promote more free trade and allow there to be more jobs in export industries for the UK. The public was told there would be no loss of sovereignty. Rumours of a gradual move to political and monetary union were downplayed or denied. The public voted Yes to such a Common market.
There was no majority then, and no majority subsequently for the UK to join a political and monetary union. The UK refused to join the currency union, negotiating an opt out from membership at Maastricht. The UK successively negotiated opt outs or preserved a veto for the Social Chapter, the common borders, common defence and security, common taxation and criminal justice. The Conservative opposition voted against the Nice, Amsterdam and Lisbon Treaties on the grounds that they still gave away too much governing power. The Conservative majority in the present government believes the UK needs a different relationship, as it does not accept the large transfers of power that have occurred in recent years.
We now find the Euro area members wishing to move further and faster towards a political union. They seek a banking union and a fiscal union of sorts. The UK cannot possibly join member states in such a move. As so many of the arrangements and Treaty agreeemnts are once again being reviewed, the UK wishes to review its relationship with the emerging political union it cannot join.
We seek a relationship based on trade and friendship, where the Uk will join other member states in doing things together where it is mutually advantageous so to do. If our signature is required on any new Treaty, we will need amendments for us that give effect to this wish for a different relationship.
The UK has been a good European by not joining the Euro. UK membership might have badly damaged the single currency by now, given the size of UK banks and the need for frequent currency adjustments both ways against the Euro over the last decade. As far as we are concerned the EU is a voluntary association of democratic states. Just as some states now want more EU power over them, the UK now wants less. It is important to accommodate both sets of wishes, to have a happier and more successful EU.