By Alex Stevenson
Angus Robertson is in a good mood. Given the SNP's strong electoral showing against Labour in last week's European elections that's no surprise.
For the Scottish nationalist leader in Westminster has reason to be cheerful. In Scotland the SNP took 29 per cent of the vote, two per cent more than the Conservatives got nationwide. This makes the SNP "the most successful party in the UK electorally" by Mr Robertson's reckoning.
"Conventional wisdom would say government parties in mid-term see their votes go down. Well the SNP of course is in government in Scotland and our vote went up ten per cent," he says gleefully.
That's true, but the Labour party is also in government - and it's had a lot longer to make Scottish voters angry than the administration in Edinburgh.
Mr Robertson disagrees. "It tells you a couple of things: the SNP is doing very well, the SNP is delivering," he insists. The SNP won in 22 out of Scotland's 32 council areas and came close to victory in a further five. First minister Alex Salmond would like to see the party up to 20 seats in the Commons at the next general election.
"I think it puts us in a very strong challenging position for the next Westminster election," Mr Robertson says. That would be a huge improvement on the party's current total of seven. It may be possible yet.
Given the calamitous result in Scotland for Labour it makes sense that the nationalists call for a general election sooner rather than later. In fact later today the SNP, together with Plaid Cymru, will use their half-day opposition day debate to call for the dissolution of parliament in the wake of the expenses scandal.
Mr Robertson explains: "There is a profound lack of confidence and legitimacy in the House of Commons, largely though not exclusively down to the expenses and allowances debacle.
"In our view, and in the majority of the view of the public, the only way to regain trust in the House of Commons as an institution is for people to be able to elect that parliament again, so they can re-elect those MPs they can trust, get rid of those that they don't and elect others that might do a better job of that.
"I just don't see how credibly this current parliament can reform itself."
Listen to the interview in full:
There's not just a need for a genera election - it's also perfectly feasible to do so, he argues. Sir Christopher Kelly's review is currently in progress and the government's plans will take a while to filter through. "The course has been set, there's no reason why we can't take three weeks out and let the public decide."
Although the nationalist motion is expected to attract the support of the opposition parties - the Conservatives, in particular, have been vocal in their calls for a general election as soon as possible - Mr Robertson concedes most Labour MPs would find it hard to support it.
"Labour are caught between the abyss and oblivion and it's kind of difficult to make a choice in that circumstance," he says. "I think some people would just like to hold on to their jobs for another few months, hope they can somehow pull back from the black hole they're looking into now."
There's a degree of sympathy there - but also a determination to make the most of Labour's trials and tribulations.
Despite its electoral situation the result it's still Labour which holds a majority in the Commons, though. This means the motion is likely to be defeated, but that doesn't deter Mr Robertson in the slightest.
"If that were the argument then nobody would have tabled a motion on the Gurkhas and that wouldn't have won," he presses.
Building on his theme, Mr Robertson expands to call for much wider reforms of parliament. Fixed terms, "beefed-up" select committees, proportional representation are all on his agenda.
"Maybe with this cold bracing wind of reform we're all feeling on expenses we should have a reform election, a historic election about reforming our democratic institutions," he says. "I think that would reinvigorate politics, I think it would help rebuild trust by the voting public."
The ultimate plan for the SNP goes well beyond the next election, of course. From the small fry of expenses, through wider parliamentary reform, we come to the big issue which has become its raison d'etre in recent years.
"After all, democrats should embrace the public having their say," he finishes.
"At least there's a continuity in message about our dissolution vote in the House of Commons and the referendum we want to put forward so Scotland can enjoy the normality of independence and become the successful country we wish it to be."
Unlike today's opposition day debate, that's a vote the SNP may yet win. Labour have a majority in the Commons but, judging by their recent showing in the European vote, the SNP's agenda remains a major threat north of the border.