The prime minister has mounted a fresh defence of the Union, based on common values and institutions.

Writing in Tuesday's Telegraph newspaper, Gordon Brown described the partnership as being based on a "covenant" binding together England, Wales and Scotland in a way that will "benefit all".

Brown said that 10 years after devolution "it is time now to explain how the Union can benefit all of us, and not at the expense of each other".

"There is no Scotland-only, Wales-only, England-only solution to transnational challenges that range from terrorism to foot and mouth disease, and from avian flu to security and climate change," he argued.

"So for these islands an environmental Union, a security Union and a Union for defence is to the benefit of all.

"But what matters even more are the common values we share across the United Kingdom: values we have developed together over the years that are rooted in liberty, in fairness and tolerance, in enterprise, in civic initiative and internationalism."

The Scot said that it is these values that lie behind "the popularity of our common institutions" such as the NHS, BBC and the monarchy, "and even more recently, in UK-wide support for the Olympics, Children in Need, Comic Relief, Make Poverty History and action on climate change".

"There is a modern case for the Union, and it must be heard," he concluded.

"It is not about partnership at the expense of pride, or about pride that can be satisfied only by sacrificing partnership.

"Instead, it is to ensure that each region and nation of the United Kingdom flourishes within a covenant and in a partnership of equals for the benefit of all."