General Election 2015: Why the real winner of Nicola Sturgeon’s rise is David Cameron

Only 8 per cent of the population has the chance to vote for the SNP but Ms Sturgeon will have a decisive role in the outcome of the election

The Conservatives are encouraging the SNP surge because it weakens Mr Miliband’s position and exposes him as dependent on the backing of the SNP if they want any chance of entering into any kind of government – Coalition or minority. (Getty Images Europe)

Nicola Sturgeon has been a popular and significant figure in Scotland for a few years now but her strong performance in last night’s TV debate shot her to fame across other parts of the UK too.

The SNP leader was largely unknown to most non-Scottish voters before the showdown on ITV – a panel of voters failed to identify Ms Sturgeon from her picture prior to the debate - but this morning, her name was the most Googled term in the whole of the UK.

She even topped YouGov’s post-debate poll, while finishing just one point behind David Cameron and Ed Miliband in an average of all four of the snap polls, suggesting there are large parts of England and Wales that are attracted to her straight-talking promotion of progressive and anti-austerity values.

The ever-growing army of SNP members will obviously be delighted with their leader’s storming performance last night and her support team in the spin room could hardly believe she had appealed to such a UK-wide audience.

However the real winner of her storming performance last night was David Cameron.

The more votes Ms Sturgeon’s SNP wins in Scotland, the slimmer the chance of Labour winning a majority.

Labour is facing the prospect of a wipe-out north of the border – it currently has 41 Scottish MPs and is heavily reliant on its support north of the border but a poll of Scottish voters last month by Lord Ashcroft showed the SNP could be on course to win more than 50 of Scotland’s 59 seats.

If this happens, it will be impossible for Mr Miliband to govern a majority government and this therefore increases Mr Cameron’s chances of serving a second term as Prime Minister.

The Conservatives are also encouraging the SNP surge because it weakens Mr Miliband’s position and exposes him as dependent on the backing of the SNP if they want any chance of entering into any kind of government – Coalition or minority. A leader in the pocket of Alex Salmond, as last month’s Tory poster depicted.

The SNP leader has dismissed the claim as '100% untrue' (EPA)

This, the Tories hope, will weaken Mr Miliband’s support in England, where voters will disapprove of the prospect of a Labour leader willing to let Scottish nationalists call the shots and dictate policy decisions.

The Tories in the spin room made no bones about their praise for Ms Sturgeon last night, eager to point out how well she took on Mr Miliband.

George Osborne openly talked her up, while Michael Gove, the Tory chief whip, put it even more plainly this morning.

"It is certainly the case that Nicola Sturgeon gave an assured performance,” he said. “Certainly the polls show that and every fair-minded person would congratulate her for that."

Labour was very aware of these tactics. Caroline Flint, Labour’s shadow energy secretary, said last night that the Tories “have got a smile on their face when they talk about Nicola Sturgeon because it helps them get back into Number 10”.

But however much they bang on about how a vote for the SNP is a vote for putting Mr Cameron back in Downing Street, they cannot stop Scottish – and some English – voters wanting to see more of Nicola Sturgeon in UK-wide politics, whether that’s in some form of deal with the governing party or in opposition.

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