Full transcript of our interview with the SNP leader, in which she discussed her party's recent surge, her strategy in the next parliament and Scottish independence

NB: The interview has been lightly edited for clarity. A shorter video interview with Nicola Sturgeon can be found here.

THE ECONOMIST: First minister, you have had six seats in the just-finished Westminster parliament. Now pollsters suggest you may soon have more than 40, even a few more than that. Can you just explain to us how this extraordinary surge has happened?

MS STURGEON: Firstly I should emphasise that I take nothing for granted. I don't look at the polls and think that we are cruising to that kind of advantage. We're going to have to work really hard to persuade people to vote SNP. We've got six MPs now, or we did before Parliament dissolved. The biggest number of MPs the SNP has ever had in the House of Commons is 11, so in a sense anything above 11 is record-breaking. We want to win as many seats as possible. Why are we sitting where we are in the polls? I think since the independence referendum campaign last year there has been a sense in Scotland that the voice that the country had during that referendum campaign should continue to be heard. People don't want to go back to the days, pre-referendum, when the Westminster establishment sidelined and ignored Scotland. They want Scotland's voice to be heard. And secondly I think people want to see more progressive politics at Westminster, they want to see a challenge to the austerity consensus and they want to see MPs in the House of Commons who are going to provide that challenge.

THE ECONOMIST: On that, you've suggested that you would be willing and indeed quite keen to support a Labour-led government in Westminster. Can you just spell out for us the terms on which that would happen?

MS STURGEON: I've said firstly that the SNP would never work with the Conservatives, either formally or informally. I've also said that I think it would be unlikely that we would be in a formal coalition with Labour. But what I have also said is that if we end up in a situation after the election—and let's remember that people are still to vote—but if we end up in a situation where there are more anti-Tory MPs than Tory MPs in the House of Commons then I would want to be part of making sure that the Tories don't get to form a government. Even if they are the largest party. I've said to Ed Miliband that if the SNP and Labour combined have more seats than the Tories do and if we vote together we can prevent David Cameron from getting back into Downing Street. That would pave the way for Ed Milliband to be prime minister. Now, what I would then say is that I don't want to see a Labour government that simply implements the same policies as a Tory government would have done. So I would want to use the influence of the SNP in the House of Commons to force a more progressive style of politics and get more progressive policies.

THE ECONOMIST: Yes. So there's the policy question, but also—especially in a rather informal arrangement—the human relationship is probably important too. On that, what are Ed Miliband's biggest weaknesses, do you think?

MS STURGEON: I'm not going to get into that kind of discussion. I don't know Ed Miliband as a person particularly well. The leaders debate last week was, I think, the second time that I've met him. I'm not in a position to judge that. It's for voters to look at leaders and make their own judgements on leadership qualities or lack of qualities—and that applies to all leaders. What I've said though is that I'm willing, in order to keep the Tories out of government, to be part of that anti-Tory alliance that could pave the way for Miliband to be Prime Minister. And what I absolutely believe is that Ed Miliband will be a better prime minister if he's got the influence of a big team of SNP MPs encouraging him, perhaps forcing him, to pursue anti-austerity policies, not to renew Trident, to protect the NHS from further privatisation. That's the kind of progressive politics that I want to see at Westminster. And that's what I want to SNP to be part of.

THE ECONOMIST: But you would in any circumstance be a junior partner in that arrangement. You're not going to write the government's policy across the board. You do see Labour therefore as a progressive party; certainly as compared to the Tories.

MS STURGEON: Oh I think Labour should be a lot more progressive. I mean I don't want to see another Tory government. Tory governments are bad for Scotland. I joined the SNP when I was 16 years old because I had a lot of disgust what the Thatcher-led Tory government was doing to the country and the communities that I lived in. But I think Labour’s mistake in recent years has been to almost end up emulating the Tories, of being a carbon copy of the Tories, rather than ploughing their own progressive furrow. So the last Labour government was elected on a wave of optimism and hope that ended up imposing tuition fees, it started the process of privatising the NHS in England and of course it led the country into an illegal war in Iraq. So I think Labour could be a lot more progressive and I think the influence of a big team of SNP MPs would be to help make it more progressive

THE ECONOMIST: In terms of your Scottish agenda—still working towards greater devolution of Scotland and then eventually, you hope, an independent Scotland—how would such an arrangement, an SNP-backed Labour government, further that agenda?

MS STURGEON: Well it's no secret that the SNP wants Scotland to be an independent country. I'm not writing any front page headlines with that revelation. But independence is not the question on the ballot paper in the general election. A strong vote for the SNP in the general election is not going to lead to another independence referendum. There will only be another independence referendum if a party, presumably the SNP, has that in a manifesto for a Scottish Parliament election and then wins sufficient numbers of seats to get that legislation through. A vote in the Westminster election is a vote to give Scotland much more clout, influence and a louder voice at Westminster. And to play a part in changing Westminster politics for the better. In terms of the Scottish context, the other point I would make is that the SNP is a party of government in Scotland. We've got considerable experience in government. We had four years as a minority government so getting things done in a minority government scenario is something the SNP has lots of experience around. We know how to get things done. We were a successful, effective and stable minority of government and that is experience that we would be able to bring to bear if there is a minority government situation in the House of Commons after the election.

THE ECONOMIST: Nonetheless, I think it's fair for us to assume that an independent Scotland still is always going to be high on your policy agenda. Do you think that will come in your political lifetime?

MS STURGEON: Yeah I do believe Scotland will become independent. I will repeat the point: firstly, I don't think I'm telling you anything you don't already know: that I want Scotland to be independent. But that's only going to happen if people in Scotland vote for that in a referendum. People then ask the question, well how can we trust the SNP to play a constructive part at Westminster if ultimately you want Scotland to be independent? Just to answer that absolutely straightforwardly: for as long as Scotland is part of the Westminster system, and that's the situation just now, it really matters to people in Scotland that there are good decisions made at Westminster, that there are good policies passed at Westminster. The SNP stands for Scotland's best interests, and as long as we're part of the Westminster system then we will play a constructive and positive part at Westminster to try and get the best deal for Scotland. And in the process of doing that, as it happens, I think we'll be able to pursue and progress policies that will be good for people in other parts of the UK as well.

THE ECONOMIST: Is there any possibility that they will actually makes a second independence referendum less likely because the Scottish cause is shown to be represented well in Westminster?

MS STURGEON: You can spend a lot of time thinking tactically through all of the “what ifs” about the outcome in terms of what it means about Scottish independence. Actually, Scotland will only become independent when a majority of people, for positive reasons, decide that Scotland should become independent. So the positive case for independence has to be made, and will have to be won in a referendum, before Scotland becomes independent. This Westminster election is about how does Scotland's voice, as part of the Westminster system, get heard as loudly and as progressively as possible? And that what a vote for the SNP is about on May 7th.

THE ECONOMIST: But you have a role to play, don’t you? It was SNP action that led to the referendum last year. What do you want to do in the next parliament to make Scotland independent?

MS STURGEON: [START OF MS STURGEON’S ANSWER NOT RECORDED] During the referendum campaign, anybody who came here at all was pretty, whatever their views on the referendum, impressed by the level of public engagement. So one of the things that has changed in Scotland, which is why I think Labour's campaign in Scotland is running into so much difficulty, is because people are very well informed, they're well educated, they're perfectly capable of making their own judgements on things. So, my principal responsibility by a country mile, my most important responsibility is governing the country well, with no ulterior motive other than to govern the country well—and that's what I'll focus on doing. And if in the process of doing that people see the benefits of decision-making powers resting in the Scottish parliament rather than Westminster…

THE ECONOMIST: So independence as a by-product rather than a fundamental objective.

MS STURGEON: I'm the first minister, so my fundamental objective every day when I get out of bed is to take good decisions and run the country well, competently and with a bit of vision, ambition and all of that. So that's what I've continued to do and I think within a process in Scotland of people gaining more confidence, of questioning why we should be at the mercy of Westminster, it’s a decision we can't always control. I think that process is under way. Where it ends up and on what time scale I can't answer now, to be perfectly honest. I can’t tell you when there’ll be another independence referendum. I think there will be one and I think there will be a ‘yes’ vote. But when that's likely to be, at the moment, is a question I can't answer with any certainty.

THE ECONOMIST: On that point about a competent government, the SNP, or the Yes campaign as a whole, seemed to get its expectations about the oil price quite badly wrong during the campaign and there doesn't seem to be that much recognition of that fact. Should that give us cause to worry about the SNP’s ability as fiscal managers?

MS STURGEON: No it shouldn't. I mean, if you take the oil price very directly, interestingly Robert Chote [chairman of the Office of Budget Responsibility] went before a Scottish parliamentary committee last week (and I'm not trying to put words in his mouth; you can go and read the official record of what he said in case I'm misrepresenting him in any way unintentionally) and he was making the point about the difficulty of projecting oil revenues. When we were projecting, as we did in the referendum campaign, $110 a barrel the Department of Energy and Climate Change was projecting an oil price of I think $128 a barrel. People got their oil projections wrong because nobody foresaw what was going to happen to the oil price. The oil price will undoubtedly go up again. Oil was never, and never has been, the absolute linchpin of the economic case for independence.

THE ECONOMIST: It was quite a prominent part of it though, wasn't it?

MS STURGEON: Sure, and sometimes that was made so by others, not the SNP, or the Yes campaign. Oil is a massive advantage for the Scottish economy, but here is one of the statistics I've been using recently to illustrate the point I’m making: if you take oil revenue projections to the end of the decade and assume they don't change, and that the oil price doesn't go back up (and that's what we're looking at), by the end of the decade, oil revenues will be £3 billion lower than they are just now. But our onshore revenue as a country, and non-oil revenues, are estimated to be £15 billion higher than they are just now. So what does that tell you? Scotland's non-oil economy is strong. I think it could be stronger with new powers to incentivise and encourage a greater non-oil growth, but it also tells you that Scotland's deficit (and we're not unique in being in a deficit position) is reducing as we go towards the end of the decade.

THE ECONOMIST: But you have got the highest budget deficit, regionally, in the country.

MS STURGEON: Well, GERS [Government Expenditure and Revenue Scotland] figures that came out just a few weeks ago show the decline in Scotland's deficit compared to the year before. In two out of the last four years, Scotland has been in a relatively better position in terms of the deficit than the UK. Fortunately the long term position, if you go back and look at these figures over a longer period, is that our fiscal position is broadly comparable to the rest of the UK. The point that I'm making here is that oil is important. One of the big arguments we've made, and continue to make, is that we should have stewarded that resource better in the past and we should steward it better in the future. Clearly there are no regional examples other than the one that was used many times during the referendum. But oil is not the be-all-and-end-all of the Scottish economy. Far, far from it.

THE ECONOMIST: You talked about Ed Miliband and not knowing him, but you do know the Labour Party, you have dealt with the Labour Party institutionally. What are your biggest reservations about working with them? What are your worries about the arrangements after the election?

MS STURGEON: I'm not particularly worried. We won't vote for things that we think are wrong. We won't vote for Labour policies that we think are just carbon copies of Tory policies. What we will seek to do is build alliances across the House of Commons, working with the parties like Plaid Cymru as well as with Labour. And there's a lot (and I know this from personal experience of some of the individuals I'm talking about) of people in Labour as back benchers—put the leadership to one side—that would find themselves a lot more drawn to some of the positions of the SNP on some of these big issues.

THE ECONOMIST: Can you imagine working with (on a case-by-case basis, not supporting a government) Tory MPs on a particular bill?

MS STURGEON: I don't want the Tories to be in power. If the Tories are a majority in England there's nothing we can do about that and that's the position we've been in many times over in my lifetime.

THE ECONOMIST: But joining with them to bring down a Labour government bill, for example?

MS STURGEON: No. I'm not going to work with Tory MPs. The Fixed-term Parliaments Act of course changes the whole scenario when it comes to possible minority government in the House of Commons. So if we decided to vote down a Labour policy that we thought was wrong, that doesn't mean you're voting down the Labour government. It’s actually quite a high bar to pass, under the Fixed-term Parliaments Act, to trigger an election. But in that kind of scenario it means that smaller parties in a Westminster context can have a lot of influence, not to bring down a government, but to force a government to take a different direction.

THE ECONOMIST: Stewart Hosie [SNP deputy leader] has said that the SNP would require consultation on any Labour Queen’s Speech, whereas Alex Salmond has said that the SNP’s support would be unconditional. Which of those is right?

MS STURGEON: I think you're provoking us, presenting me with these two views, to make them sound as if they're further apart than they are. I’ve said as recently ago as yesterday: if we're in a position where there are more anti-Tory MPs than Tory MPs, then the first thing we've got to do is decide whether we're voting together to stop… If (and it is an “if” because I don't know whether this is going to be the outcome) but if the Tories were the largest party but didn't have the majority, the first thing to do would be to stop a Tory government from getting off the ground.

THE ECONOMIST: Without imposing conditions on any other parties?

MS STURGEON: Well I want to stop the Tories. No, after that we would seek to use our influence to make sure a minority Labour government was delivering policies we thought were in the interest of Scotland and the rest of the UK. I hesitate to go much further than that because I do think there is a point which you reach in these discussions where you start to treat the voters as if they're incidental in all of this, if you get too drawn into the minutiae of what happens afterwards.

THE ECONOMIST: Well they do deserve—it’s quite a big question—to know: will you unconditionally support the creation of a Labour government? Not necessarily its bills, I accept that, but would you unconditionally support the creation of a Labour government? That seems to be something Scottish voters deserve to know.

MS STURGEON: If we have the numbers to do it and Labour were prepared to do it we would block a Tory government. We would then seek to use our influence. I’m not going to get into exactly how, practically, that would work because some of that would depend on the numbers. It will will depend on what Labour are putting forward. But we would seek to use our influence to make sure a minority Labour government was delivering the things we thought were right for them to do.

THE ECONOMIST: You've talked a lot about the prospect of EU referendum, particularly under a possible Tory government. English voters might turn around and say: is it fair for the SNP to deny the rest of the UK a vote on whether or not Britain should remain in the EU when Scots had a say on their own possible secession from the UK?

MS STURGEON: I'm simply giving my view. I don't think there should be an in-out European referendum.

THE ECONOMIST: In any circumstances?

MS STURGEON: I don't favour an in-out referendum. I do think there are things about Europe that should change, but I think they should be pursued in a way different to how the Tories are doing it in terms of threatening a referendum. I think David Cameron is playing a very dangerous game with the referendum: pandering to the UKIP, taking the UK further and further, potentially to the exit door. So I'm just being open and honest about that. If people want to vote—if an EU referendum is the issue that means so much to them—then there are other parties that they can vote for that have that as a policy. But it’s not the policy of the SNP.

THE ECONOMIST: If the UK were to vote to leave the EU, but Scotland had not done the same, would that be a case for another referendum here?

MS STURGEON: I think if we ended up being taken out of Europe against our will then I think there would be an awful lot of people in Scotland saying that we need to look at independence again. Because we don't want to be taken out of Europe. I've put forward the proposal that before we come out of Europe in a referendum then each of the four parts of the UK should have to vote for that, not just the UK.

THE ECONOMIST: But that's not going to happen.

MS STURGEON: But why, who knows it’s not going to happen?

THE ECONOMIST: Because the referendum would only happen if the Tories were in power which we know is not going to happen…

MS STURGEON: Well I will continue to argue what I think is right. I think it would be unconscionable for any part of the UK to find itself outside of the European Union when they had voted to stay in. I think that would be an indefensible position.

THE ECONOMIST: And that is the next likely trigger for another Scottish referendum?

MS STURGEON: I don't think there should be an in-out EU referendum and if there is one, I think the circumstances and the arrangements for that referendum should guard against any part of the UK being taken out against our will. If I don't prevail on both of these things and we're in a referendum I'd be arguing, I hope, for the UK to stay in. But if we end up in the situation that I don't want us to be in, where Scotland has been taken out of the EU against its will, I think (whatever I might say about it) there would be significant numbers of people in Scotland saying, hold on a sec, we don't want that to happen.

THE ECONOMIST: You have a message which pretty much horrifies people south of the Scottish border, but nonetheless: there seems to be a strong possibility that you could be quite popular south of the border. So you have a tough message for most English voters, but it seems that you can override some of their hostility to politicians. Can you just explain to us how that's so?

MS STURGEON: I think how the message of the SNP is sometimes presented (to use your terminology not mine) is horrifying to voters. I think what we see in my email inbox, which is absolutely overflowing with messages from people in other parts of the UK after the leaders' debate, is that when people actually hear what the SNP is all about then they see a very, very different reality from what they're told.

THE ECONOMIST: What about the personal style? The leaders of our mainstream parties all poll pretty pretty badly, sometimes differently from their party. Sometimes personal style matters.

MS STURGEON: Sure. One of the things I've been told—it’s difficult for me to get a sense of this myself—is that what people liked in the leaders' debate was seeing, very visibly, a very different style of politics. I think people liked seeing, frankly, some women's voices in there as an alternative to the old-boys’-network view of Westminster that they usually get. It's one of the features of increasingly having a multi-party system that people see choices that they previously didn’t know were there—and I think that's a good thing. I accept it's only on the basis of the people who are taking the time to contact me, but a lot of people across the UK see that as a breath of fresh air.

THE ECONOMIST: No SNP candidates in England?

MS STURGEON: [Laughs] Despite the temptations and the encouragement, no.

THE ECONOMIST: I heard rumours that Berwick was being considered as a foothold.

MS STURGEON: I think we'll continue to focus on Scotland.

THE ECONOMIST: It’s the 700th anniversary of the siege of Carlisle this year...

MS STURGEON: [Laughs] Don’t tempt me.

THE ECONOMIST: Thank you.