Amid all the sound and fury over Scotland's membership of the European Union, it is refreshing to read Professor William G Naphy's clear argument (Letters, December 13).

Part of the confusion in many minds is the impression given, over a long time, that the United Kingdom is a unitary state. Thus, for many foreign folk and many English people, the name England is synonymous with the UK. From that follows the belief that Scotland is a region, not a country.

To some extent, this erroneous belief is easy to understand. The United Kingdom is an unique, artificial construct, knowledge and understanding of which is probably totally lacking in the rest of the world.

The Treaty of Union was between two sovereign states, albeit with a single, shared monarch. But that treaty did not destroy those states. Scotland and England remain separate and distinct kingdoms. The fact they share a parliament does not change that.

Therein lies, I am sure, the confusion in the mind of Jose Manuel Barroso. I submit that the same confusion exists in the minds of most people in the UK.

At present then, while the UK is signatory to the Treaties of the European Union, that signature is, implicitly if not explicitly, on behalf of both countries of the UK.

Prof Naphy's second last paragraph is highly relevant, explaining the difference between succession and secession.

If, in a not-so-hypothetical referendum on the UK's continued membership of the EU, England voted to leave the UK but Scotland voted to stay, where would Mr Barroso stand?

John Scott Roy,

42 Galloway Avenue,

Ayr.

Peter Russell asserts that Scotland will be better off by remaining part of "the most successful political and economic union in history" (Letters, December 11). This mantra is regularly trotted out by the Better Together camp, but I have seen little evidence to back it up.

A case might be made that the British Empire, at the height of its powers, fitted the description. Back in 1900, after all, England and Scotland were at the heart of the largest and richest empire on the planet, encompassing 300 million people or 22% of the total global population. But that was then. The empire is long gone, and 50 countries and more have since chosen the path of independence. Today the UK, with 63 million people, accounts for just 0.89% of the world's population.

GDP per capita is a particularly relevant indicator. In 2011, GDP figures from the IMF ranked the UK at a lowly 22nd place – representing a substantial fall over the preceding century. Countries formerly in the empire such as Singapore, Australia and Canada now occupy much higher GDP rankings (third, 11th and 14th), while GDP in no fewer than 12 European countries has surpassed that of the UK. And one would not bet against the UK's position slipping further in the coming years.

The referendum debate is not helped by over-inflated claims about the Union.

The economic choice facing Scotland in 2014 will be between staying in and accepting the UK's gradual but continuing post-empire decline, or, like other countries of the former empire, choosing to stand on our own feet and move forward.

DB Williamson,

3 Rosebery Place,

Dunbar.

Gordon Ingram and the Rev Archie Black both make sensible and reasoned points (Letters, December 12). Just because Jose Manuel Barroso seems to assume the United Kingdom is a continuation of the pre-Union English state does not make it true or legally well-founded.

In 1707 the parliaments of two sovereign nations signed a treaty which united them in a new state called The United Kingdom of Great Britain. At a later date Ireland was incorporated into that Union but was already a vassal state of England, as had been Wales by right of conquest since the reign of Edward I.

It is vital to recognise the difference between Scotland's status within the Union and that of the other Celtic nations. Scotland was not a conquered nation and the Treaty of Union was supposed to be between two equal partners. Although the English establishment has behaved towards Scotland ever since as if she was acquired in the same way as Ireland and Wales, there is no legal or historical basis for that assumption.

That is why the Holyrood Government is entitled to say that Scotland should not be treated as a new applicant to the EU. Any argument to the contrary is on extremely shaky moral and legal grounds.

David C Purdie,

12 Mayburn Vale,

Loanhead,

Midlothian.

WHILE I fully agree with points being made by Iain AD Mann on Scotland and the EU (Letters, December 13), I feel it only fair to point out that the prospect of Catalonia's secession from Spain is unlikely to raise hackles in Jose Manuel Barroso from a national point of view.

He is, of course, Portuguese. Despite a later aberration of 60 years under Spanish rule (1580-1640), Portugal declared its independence from the kingdom of Léon in 1139. While Mr Barroso is perhaps opposed to Catalonia being independent, I can't imagine he would relish being called a Spaniard.

Michael Rossi,

66 Canalside Gardens,

Southall, Middlesex.