It is fitting that in the year of Plaid Cymru's ninetieth birthday Wales is finally emerging from the UK's political shadows and is a factor in this, the closest of elections.

Plaid Cymru was formed in 1925 by those who sought the recognition of Wales as a political entity.

Although the two main political forces at the time - the Labour and Liberal parties - both notionally supported the cause of Welsh home rule, they failed at each opportunity to deliver it.

T'was ever thus.

No-one can deny that Wales exists today as a political entity in its own right because of that decision ninety years ago to form Plaid Cymru.

And since the founding of the Scottish National Party almost a decade later, our two parties and our two causes have reflected the warm friendship between our two countries.

That bond has seen us sit together as one group in the parliaments in Europe and at Westminster and will continue when we secure the largest ever bloc of Plaid Cymru and SNP MPs in May.

Close relations between leading figures in both our parties has provided a solid foundation for political cooperation.

Dafydd Wigley and Alex Salmond were a formidable double act in the Nineties when they both served as party leaders and as members of parliament.

And to this day, I am proud to work closely with my counterpart and friend, First Minister Nicola Sturgeon.

In her, Scotland has a leader that is making Scotland stronger and her UK-wide presence is ensuring your country's prominence at any level where Scottish interests are at stake.

I look forward to my relationship with her to evolve further next year with us both leading the respective governments of our countries and working together in pursuit of our shared goals.

The immediate priority for now us is to ensure that the progressive alliance we have formed is successful in May's election.

It is a natural alliance demonstrating a new politics, born in Scotland during the referendum, where the old politics gave way to alliances built on cooperation and common purpose.

There are three strands of Plaid Cymru's outlook that characterise our political personality, and contribute to that progressive alliance:

  • The advancement of Wales constitutionally as a nation, for greater self-government and ultimately as an independent country whilst strengthening our unique cultural character.

  • Economic and social justice, where public services are cherished and kept in public hands and where inequality is closed and prospects enhanced.

  •  Meeting our global obligations as internationalists as positive contributors to the global community in the cause of peace and justice and in playing our part in efforts to meet the climate change threat.

On that basis it is easy to see why we can find common cause with the SNP and progressives in England as part of a broad alliance to shift the political narrative away from austerity and inequality and towards an alternative.

This election is not only the first proper multi-party election at a UK level it is the first real multi-national election for the UK.

The inclusion of the Party of Wales and the SNP in the televised leaders' debates, the progressive aftershocks rippling through these islands following the independence referendum and the growing realisation that the Palace of Westminster has ceded its sovereignty to people, mean that a permanent rebalancing of power and wealth in the British State is not just possible - it is inevitable.

I - and the SNP - have made it clear that our alliance will lead to us cooperating closely in any negotiations that may occur in the event of a hung parliament.

We've been explicit in our vision for that outcome:

  • Austerity giving way to investment-based economic recovery.

  • No renewal of Trident nuclear weapons.

  • Empowerment for the nations of these islands.

Our success in achieving these aims would benefit communities across the UK and I believe will change the complexion of politics everywhere and forever.

It would lead to the empowerment of people not only in Wales and Scotland but in those forgotten and neglected parts of England that have been disadvantaged by the centralisation of wealth and opportunities to the City of London.

In addition to all this, it is my view that the multi-national nature of this election must result in a 'multi-nationalisation' of the British State itself.

We can never go back now to the old ways at a UK level.

That means not simply the transfer of wide-ranging functions from Whitehall to the devolved administrations, it means a voice for all nations in decisions that are made on behalf of us all at the UK level.

The people are sovereign and UK institutions and decisions should multi-nationalise to reflect that.

Joint decision-making between the governments of the UK is essential because the lob-sided nature of Westminster is so out of touch with the reality on the ground.

From the Bank of England, to the Supreme Court and on matters such as foreign policy and social protection, the UK must now multi-nationalise.

All this is arguably - for the first time - in our hands at this election.

Let's seize that opportunity.