More than 1,800 people have joined the SNP following Nicola Sturgeon's success in the leaders debate.

The party's general election campaign director Angus Robertson said last night that over 1,200 people joined during the two hour long ITV debate.

However, this figure has now risen to more than 1,800.

The party also tweeted out a picture during the debate of Sturgeon with David Cameron, Ed Miliband and Nick Clegg in her pocket captioned 'we're going to need a bigger pocket...'.

The picture was a reworking of a Conservative poster which featured an image of Alex Salmond with Miliband in his pocket.

Sturgeon emerged triumphant from her historic appearance in the televised debate with one snap opinion poll handing victory to the SNP leader.

 A YouGov survey of 1,100 people found  the First Minister performed best during the seven party ITV shootout last night.

Ms Sturgeon was named by 28 per cent of those questioned, followed by Ukip leader Nigel Farage on 20 per cent, Prime Minister David Cameron on 18 per cent and Labour's Ed Miliband on 15 per cent.

She also outpolled her opponents when YouGov asked people for marks out of 10, scoring 6.7 to Mr Miliband and Mr Cameron's 5.9

In a ComRes poll, the SNP leader also performed strongly, with 20  per cent, just  behind Mr Miliband, Mr Cameron and Mr Farage on 21 per cent. 

ICM put Ms Sturgeon fourth behind the Labour, Tory and Ukip leaders, with 17 per cent of people saying she had had the best night. She was far ahead of Liberal Democrat leader Nick Clegg on nine per cent.

In the immediate aftermath of the debate the SNP hailed an average of the three polls which placed Ms Sturgeon as the winner. 

However, a later poll by Survation suggested Ms Sturgeon was 10 per cent behind Mr Cameron and Mr Miliband who both polled 25 per cent. 

The Nationalists also said 1,600 people had joined the party during the two-hour showdown which saw the SNP leader try to ease English voters' growing fears about her party. 

She appealed above the head of the other party leaders to tell people south of the border that the SNP would be their "allies" in the fight against NHS privatisation.

After the debate the Tories turned their fire on the SNP leader, updating an attack poster, which had originally featured Alex Salmond, to now show Ms Sturgeon with the Labour leader in her pocket.

During heated exchanges in the two-hour showdown, Mr Farage told the  First Minister that English people were "cheesed off" at the amount of money "going over Hadrian's wall" as he called for a £5 billion cut in the Barnett formula.

Mr Cameron was heckled by a female member of the studio audience who shouted that the Tories were not listening to ordinary people's concerns.

The Prime Minister faced the brunt of criticism from many of the party leaders during the event, the only debate the Conservative leader has agreed to take part in in the run up to May's vote.

LibDem leader Nick Clegg accused the Prime Minister of abandoning the course pursued by the Coalition in favour of the poor taking more of the brunt of cuts.

Labour leader Ed Miliband also hit out at Mr Cameron, accusing him of planning "extreme" measures to reduce public services after May.

He also told Ms Sturgeon that "the reality is that SNP cuts are just the same as Tory cuts".

Ms Sturgeon's call saw her repeat her message of friendship towards English voters to a television audience totalling potentially millions. 

The SNP hope that by winning over Labour voters in England it will make it harder for Mr Miliband to reject the SNP if he needs their votes after May 7.

A poll for the Herald by TNS this week found that around 29 per cent of Labour voters were relaxed about SNP influence on a Labour government.

The Tories have been on the offensive against the SNP, a strategy many senior Conservatives hope will increase support from concerned English voters. 

Mr Cameron's aides later said a Labour government propped up by the SNP would mean "£148bn more debt, unlimited benefits and weaker defences with Trident scrapped".

Labour claimed that Mr Clegg and Mr Cameron had both "blamed each other" for the failures of the coalition over the last five years "and they are both right".

There was also criticism of Mr Farage with accusations his party was encouraging scaremongering on a range of issues.

Leanne Wood, the Plaid Cymru leader, told him he should be "ashamed' of himself. Ms Sturgeon accused him of "intolerance" and suggested that there was nothing he would not blame on immigrants after he claimed that foreigners were coming to the UK to access free HIV drugs on the NHS.

SNP MP Stewart Hosie said that Ms Sturgeon did well because  she was able to "get the volume of her message across very well on anti-austerity, anti-Trident and keeping the NHS in the public sector. We are incredibly pleased."

A senior Labour source insisted Mr Miliband had come across as the most competent, building on last week's TV debate. 

"It was interesting to see how the Prime Minister hid behind Nicola Sturgeon and Leanne Wood," he said.

Last night, Rupert Murdoch tweeted: "Great performances by SNP Sturgeon and Ukip Farage. Cameron sort of okay, Miliband not, Clegg pathetic."