Ed Miliband struggled to connect with a young Labour supporter after the young boy was overcome with nerves.
Edward, 5, was waving a home-made sign but when the Labour leader stopped to shake his hand he did not seem to know what to do.
In the end Mr Miliband took the sign but still could not persuade shy Edward to shake his hand.
Boris Johnson has said Ed Miliband "would do more damage to this country than he did to his brother".
The Mayor of London accused Mr Miliband of "backstabbing" in an interview with the Sun On Sunday - a reference to the Labour leader's victory over his brother David in the party's leadership contest in September 2010.
In a heated exchange on the BBC's Andrew Marr Show, Ed Miliband suggested Tory election adviser Lynton Crosby "had put" Boris Johnson up to the comment, telling the Mayor of London: "Come on Boris, you're better than that - don't just do what Lynton says to you."
But Johnson hit back, saying: "I'm not saying your brother presented himself at A&E with a dagger in his back but he [Ed Miliband] would do more damage to this country than he did to his brother".
Ed Miliband has ruled out a confidence and supply deal with the SNP after the general election.
Asked if he would negotiate with SNP leader Nicola Sturgeon in the event of a hung parliament, Mr Miliband told the BBC's Andrew Marr: "It's not happening".
The Labour leader added: "I want to be clear about this. No coalition, no tie-ins. I'm not doing deals with the Scottish National Party."
Mr Miliband had already ruled out a formal coalition but had so far declined to comment on a potential looser arrangement with the Scottish nationalists - which had been seized on by the Conservatives.
He accused the SNP and the Conservatives of wanting to "set England and Scotland up against each other", promising his party will represent the whole of the UK.
Labour leader Ed Miliband has revealed he is "quite sympathetic" to having more bank holidays, economic impacts allowing.
Asked about Ukip's proposal for St George's Day to be designated a new bank holiday, he told LBC radio: "I am quite sympathetic to more bank holidays.
"But you have to be careful about what it means for the economy and all that," he added.
Mr Miliband said he had not marked St George's Day this year but it was "always nice to celebrate it by campaigning in England".
England means a whole range of things. It means a sense of fair play, it means incredible countryside, it is obviously the place where my parents took refuge after the Second World War so it means a huge amount to me.
David Cameron insisted that there was a post-conflict plan for Libya and said that he made the "right decision" to stop Muammar Gaddafi.Read the full story ›
Labour leader Ed Miliband has been accused of "politicising a tragedy" by claiming that the coalition's lack of planning in post-conflict Libya was partly to blame for the migrant crisis.
Conservatives have accused Labour of drawing the link far too closely between David Cameron and the migrant deaths in the Mediterranean.
But at a news conference today, Miliband remained defiant, saying: "I don't think anybody in the foreign policy community or in the wider international community would disagree with what I have said, about the failure of post-conflict planning."
ITV News Political Correspondent Carl Dinnen reports.
David Miliband has revealed who he's voting for in the General Election ... and unsurprisingly it's Labour.
Sharing a picture of his postal ballot envelope on Twitter, Ed Miliband's brother and one-time political opponent said he was "proud" to have voted for the party.
Conservative ex-foreign minister Alistair Burt has accused Ed Miliband of "selling short" the work of British diplomatic staff and others in Libya.
He tweeted his response after the Labour leader suggested today that UK failures in Libya in the aftermath of the fall of Muammar Gaddafi were partly to blame for the refugee tragedies in the Mediterranean.
Mr Burt wrote: "Sorry Ed Miliband, I visited our people who worked day in day out to rebuild Libyan institutions for months/years after 2011."
1. Sorry Ed Miliband- I visited our people who worked day in day out to re build Libyan institutions for months/years after 2011.
2. I don't recall them abandoning Libya. I recall their immense effort, and how difficult things were. I think you sell UK FCO a bit short.
Former foreign secretary William Hague has criticised Labour leader Ed Miliband after he attacked the government's strategy on Libya.
He said: Foreign policy is not something that you can just discover 13 days before polling day. This is the first time in five years that Ed Miliband has troubled himself to make a full length speech on foreign policy."
"So I would say to him that he cannot lecture anybody about British influence in the world when the last Labour government closed more than 30 of our embassies, never had a foreign secretary visit Australia in 13 years, withdrew from Latin America, closed the language school of the Foreign Office - all things we have had to put right under this Government.
"He cannot come to foreign policy with some ill-judged, opportunistic remarks after five years and say, 'maybe this will tackle it'", he added.
David Cameron has said Ed Miliband's remarks that imply the Mediterranean refugee crisis is "in part a direct result" of the government's military intervention in Libya in 2011 are "ill-judged".
I've learnt as prime minister that it is so important in a dangerous and uncertain world that you show clarity, consistency and strength on these foreign policy issues.
And I think frankly people will look at these ill-judged remarks and they will reach their own conclusion.