Why are we asking this question now?
Because of the mounting evidence that in terms of both legislation and public policy, huge differences are emerging between England and Scotland. Education and health are key areas of discrepancy, the latest example of which highlights the fact that thousands of people could lose their sight because of a decision not to supply on the National Health Service drugs that tackle a leading cause of blindness. Unless, that is, sufferers from age-related macular degeneration - the most common form of blindness - have the fortune to live north of the border. The preliminary ruling on the subject by the National Institute for Health and Clinic Excellence applies only to England and Wales and the drugs in question are already available on prescription in Scotland.
It is a small but emotive addition to the growing list of the distinctions between the way that England, Scotland, Wales and Northern Ireland are ruled, with a knock-on effect on the everyday lives of the citizens of the nations that constitute the United Kingdom.
The issue has been brought into dramatic relief over the past six weeks with the election of a minority Scottish Nationalist administration in Edinburgh, the growing possibility that Plaid Cymru could have a share of power in Cardiff, and the restoration of devolution to Belfast.
What is driving the nations apart?
In a word, devolution. A key Labour policy commitment in 1997 led to the creation of the Scottish Parliament and Welsh Assembly two years later.
Even with Labour in office in Westminster, Edinburgh and Cardiff until last month, differences began to emerge in the running of schools, hospitals and social services as the devolved institutions' political leaders began to stake out policy positions distinct from London.
A crucial explanation appears to be the different instincts of Scottish and Welsh voters from their English counterparts. As they are traditionally more left-wing and more sympathetic to redistribution and the public sector, Labour leaders there have been forced to champion - and implement - policies opposed by the UK government. They have also steered well clear of Tony Blair's ideas for injecting choice and competition into public services. The trend can only continue with the progress of nationalism in Scotland and, to a lesser extent, in Wales and the re-establishment of the Stormont administration in Northern Ireland after years of direct rule from London.
What differences are opening up over education?
If the Scottish education system has always been distinct from the rest of the UK, there is now a gulf between the experience of students in England and Scotland. The Edinburgh administration abolished the £1,000-a-year tuition fees for higher education and then rejected the £3,000-a-year top-up fees recently brought in for English universities.
Cardiff has swept away the school league tables system still in place in England, and nor is either nation showing any interest in opening the city academies or trust schools promoted by Tony Blair as the way of driving up standards in urban areas.
What about health and social services?
One of the first acts of the Scottish Executive was to bring in free long-term care for the elderly, leading to inevitable accounts of the different fates suffered by elderly residents of care homes either side of the border. Scottish nurses will also get their pay rise in full, thanks to Edinburgh, while their English colleagues will have to make do with a staged increase.
Cardiff has removed prescription charges and overhauled the structure of Welsh health services. Welsh pensioners have also enjoyed free bus travel for several years. Another flagship Blair policy - foundation hospitals - is virtually absent from the map of Scotland or Wales. The irony is that it would not exist in England had it not been for the votes of Scottish Labour MPs who had no influence over the health services in their constituencies.
Any other differences?
Devolution has had its impact in countless ways across the UK. The smoking ban, about to be implemented in England, is already in force everywhere else.
Scotland outlawed fox-hunting well before it was banned in England - and it would be certain to remain so even if a future Cameron government was to legalise it south of the border.
Scotland brought in mental health law reforms only now being debated at Westminster and has introduced a different freedom of information regime from the rest of the UK. Wales created a children's commissioner ahead of Westminster and is likely shortly to offer free entry to historic buildings and heritage sites.
What is the impact on England?
It is not clear whether the surge in English nationalism, with the profusion of the Cross of St George flags flown during football tournaments and the growing number of people identifying themselves as English rather than British, could be a by-product of devolution of power to Scotland and Wales.
What is certain is that the anomalies between the UK's different parts has risen up the agenda of many English politicians as constituents protest that their taxes are subsidising more generous public services elsewhere. It has also become a recurring theme in some national newspapers (although not in their Scottish editions).
William Hague, the former Tory leader, promoted the idea of an English parliament. That policy has been ditched by David Cameron, who fears it could risk the break-up of the UK, but he is expected to propose barring Scottish MPs in Westminster from voting on purely English matters.
Some Labour MPs fear Gordon Brown's arrival as Prime Minister could further focus the attention on the issue with a damaging effect on Labour's support among the fabled voters of Middle England.
What is likely to happen next?
It is inevitable that the differences will widen. The new Scottish Nationalist administration in Edinburgh is, for example, committed to replacing the council tax with a local income tax, and with the support of the Liberal Democrats, may bring in an entirely distinct system of local government finance from that in England.
There has also even been conflict over a foreign policy issue as Alex Salmond, the SNP first minister, objected to talks between Mr Blair and Col Muammar Gaddafi, the Libyan leader, over returning Libyan prisoners held in the UK, the most famous of whom is the Lockerbie bomber.
Meanwhile, Plaid Cymru is pressing for a referendum on giving the Welsh assembly the same tax-raising powers as those in Edinburgh. Labour could have to agree to the proposal to stitch together a power-sharing deal in Cardiff.
The crucial question is whether devolution will ease tensions in areas that felt they were in a strait-jacket in an English-dominated United Kingdom.
Or is it accelerating a process that will result in the break-up of the country?
So are we witnessing the break-up of the UK?
* In key policy areas that affect everyday life, there are profound differences between England, Scotland and Wales
* The Scottish Nationalists are in office in Edinburgh and Plaid Cymru's support is growing
* English nationalism is on the rise and resentment is growing that England is allegedly bankrolling Scotland and Wales
* The powers of the Scottish Parliament and in particular the Welsh Assembly are strictly limited
* There appears little real appetite for independence, with growing nationalist support arguably an anti-Labour protest vote
* Despite the differences, there is still far more that unites rather than divides the UK's constituent partsReuse content