Three of the forty constituencies in Wales elected Plaid Cymru MPs in 2010. The party’s total national vote count came to 165,000 people, not even a third of the number who voted for the BNP on the same day.

Plaid Cymru are not a big party but they are vocal, and on Thursday, their leader Leanne Wood will share a platform with six of the UK’s other political leaders, to make the case for Welsh empowerment.

Publishing their manifesto today, the party is focusing on three fronts: securing parity of powers and resources for Wales with Scotland; ending austerity, and permanently rebalancing the UK economy with targeted investment.

This was a manifesto that stuck to its roots. traditional and left-wing, the party’s economic policies read like Labour Unbound: splitting up the banks, 50p top rate of tax, Financial Transaction Tax and doubling the bank levy. This is economic re-balancing through route one re-distribution.

Some of the measures, such as demanding that the Bank of England renames itself and that its governor comes to Wales to explain his monetary and fiscal actions, are unrealistic. Others, such as calling for a Welsh Development Bank and targeted export support for Welsh businesses, show that behind this left-leaning document is a party that recognises that economic growth lies in engagement and supply-side reforms.

Taxing bankers and their transactions may not boost economic growth but giving SMEs a dedicated alternative source of localised funding is a workable policy which has performed well in successful economies such as Germany.

Plaid Cymru’s plans for investing in skills and infrastructure, and developing a new manufacturing strategy should be welcomed by Welsh voters. but some will argue that the manifesto lacks details, particularly in these key policy areas.

The strongest parts of the manifesto are where Plaid Cymru sees itself in relation to the rest of the UK. It wants to be independent, remain in the EU and have its own seat in the United Nations.

The party calls for a creation of a Welsh Treasury, control of its own corporation tax, and the establishment of a Public Bank in Wales to invest in infrastructure. Plaid Cymru’s arguments for devolution are as strong as those of the Scots, but they are muted by their relative size.

On Thursday, Leanne Wood will be asked to lay out a vision for a part of the United Kingdom which has been overlooked by much of the devolution debate raging across the country. Even though only 165,000 people voted for her party, in the eyes of the rest of the UK, she will be representing over three million Welsh people.

She alone must argue that devolution is not just a North-South debate or one between the Westminster parties and their potential governing partners: It’s about what’s the best for Britain’s working people and the businesses they work for.