Scottish politics is dominated by two fundamental questions. In common with many other west European nations, the future of the European Union is much debated. Unlike other European nations, Scotland is also dominated by the question of its constitutional settlement.

The two issues are entangled, but mean that Scots argue simultaneously over what powers should be seceded to Europe and which should be seized from Westminster.

Because of this "national question" Scotland has a four-way party split. Alongside the Labour, Conservative and Liberal Democrat parties there is the Scottish National Party. Far from devolution removing the SNP's raison d'etre, it has spurred it to new electoral heights. The fight for Scotland's future is very much alive.

Without the fanfare or much envied economic success of Ireland, Scotland has changed dramatically over the last few decades. In the 1950s more than 50 per cent of Scots voted for the Conservative Party. The Tories represented a church-going, empire-loving nation with a manufacturing economy.

Since then the empire has evaporated, the church has diminished and the heavy industry is gone. From the 1960s onwards Labour has been the largest party in Scotland. Traditionally, it appealed to the working class and Catholic vote, but by the 1970s it was the establishment party for much of industrialised Scotland.

During the 1980s and 1990s Scots voted in ever larger numbers for the Labour Party, which was seen to represent Scottish values of community and decency against the rampant market forces of Thatcher's Britain. Of Scotland's 32 local councils, Labour runs 14 outright and is a coalition partner in eight others. Of Scotland's 72 Westminster seats, 56 are held by Labour. Labour is the majority partner in the coalition government in Edinburgh.

This grip on Scottish politics has lead to accusations of a "one-party state". Instances of massive corruption at local government level in several Labour councils have tarnished the image of the "people's party".

The Scottish leader, Donald Dewar, is an avuncular figure, bookish and scholarly and much loved as the "father of the parliament". He leads a parliamentary group in Holyrood that is youthful and loyal, if perhaps lacking the star talent of the Scottish Labour party in Westminster. Despite majority support for entry into the euro, the Scottish Labour Party are bound by the greater caution of Tony Blair.

Snapping at the heels of Labour is the Scottish National Party. Formed out of an amalgam of cultural pressure groups in the 1920s, the SNP was a slow starter in the electoral stakes. The nationalists didn't take off until 1967, when they won a by-election from the Labour Party. The discovery of oil off the Scottish coast at the same time meant the economic fears many had for an independent Scotland were briefly removed, and by the early 1970s the SNP commanded 30 per cent of the vote, but only 11 Westminster seats.

The nationalists were not a united party. Beneath the independence umbrella sheltered all extremes of political opinion. Their commitment to democratic and peaceful means was not enough to disguise a confused ideological message, and Scots turned their back on independence in the 1979 general election.

Gradually, after various splits and public rows, the party adopted a social democratic agenda. If they were to ever gain power, they had to win seats from the Labour Party and they would only do this from a left wing platform. During the 1990s their share of the vote rose to 29 per cent for the election to Holyrood and they now form the official opposition in the devolved parliament.

They are lead by Alex Salmond, an economist with a permanent grin on his face, the product of permanently trying to outsmart the British establishment. He is the embodiment of "economic nationalism", which sees as the chief gain from independence the ability to transform the Scottish economy. He would love immediate entry into the euro, because it would remove the technical difficulties of forming an independent currency.

The SNP are responsible for making Ireland's economic success a political issue in Scotland. Those who think it is proof of what small nations with control of their economy can do are nationalists. Those who think Ireland is proof of what large injections of EU money can do - they're unionists.

The conservatives have fallen a long way from the 1950s. At the last British general election, they failed to win a single seat in Scotland. Though bitterly opposed to devolution and proportional representation, they are grateful for 18 seats they won through the PR mechanism for Holyrood.

Fourth come the Liberal Democrats. Liberalism has always had a strong foothold in Scotland, with the Highlands in particular sympathetic to the party that delivered crofting rights in the 19th century. The Liberal Democrats have bumped along at the 10 per cent mark in popular opinion for the last 20 years.

Scotland remains a volatile political landscape.