THERE was a huge turn-out at the Edinburgh International Book Festival this week to see a real-life grown up in the flesh: Labour's former Home Secretary Alan Johnson.

He was there to talk about his childhood memoir This Boy, an unflinching account of his difficult, poverty-stricken upbringing in London in the 1950s. He described how, with his mother seriously ill in hospital, his feckless father spent Christmas Day in the pub. The young Alan and his older sister were told not to breathe a word - or their mother would die of a heart attack.

It was one of several heart-breaking stories from an early life that would have crushed most people. Instead, as we all know, the bright, ambitious and supremely resilient Mr Johnson rose through the trade union movement to become an MP for Hull then Education Secretary (the first, he believes, to have been on free school meals), Health Secretary and finally Home Secretary.

Perhaps part of his success in politics can be explained by his character. Mr Johnson is comfortable in his own skin. He is engaging, down to earth and "talks human," a dreadful cliche but a priceless asset nonetheless. It's no surprise, then, that when another former minister, Chris Mullin, urged Ed Miliband to "bring back some of the grown-ups," Alan Johnson was top of his list.

That headline-grabbing call ensured that in his book festival discussion with Ruth Wishart, Johnson could not escape searching questions about the state of his party and Ed Miliband's leadership.

For the record, he will not be tempted back into the shadow cabinet but would accept a ministerial role if Labour wins the 2015 general election.

On Labour's lacklustre summer, which has seen the party's lead over the Tories eroded and prompted widespread sniping from within, he was dismissive. "It's the kind of August story I've seen before," he said with a shrug. "There's a feeling that the economy has picked up and the Conservatives are on the front foot, so there's an attempt to suggest the opposition should be saying more and doing more. But there has never been an opposition that laid its cards on the table too early before a general election."

Mr Johnson, who supported David Miliband's leadership challenge, said he was "very impressed" with Ed's integrity. As for the leader's personal poll ratings, which lag significantly behind his party's, that's nothing to worry about so long before the election. What about Labour's looming and potentially divisive confrontation with the unions in the wake of the Falkirk selection debacle? Ed Miliband is simply completing reforms started by the late John Smith, insisted Mr Johnson. Perfectly sensible.

Well, you should have seen the looks of relief on the faces of Scottish Labour leader Johann Lamont and Shadow Scottish Secretary Margaret Curran as they made their way out of the book festival venue. Mr Johnson's loyalty is a something of a rarity these days and they know it.

As the Labour leader arrived in Edinburgh yesterday for a stage-managed public Q&A session with voters on the decline in living standards under the Tory-LibDem Coalition he had no shortage of criticism and advice ringing in his ears. It started with John Prescott's blunt exhortation to use the Alex Ferguson "hair dryer treatment" on underperforming shadow ministers and has moved on to specific policies which might reinvigorate the party.

The latest, if adopted, could have a bearing on the referendum campaign. It's understood that Mr Miliband is under pressure from senior colleagues to push for an early referendum on Britain's EU membership. Supporters of the idea, said to include Shadow Chancellor Ed Balls and John Cruddas, the MP leading the party's policy review, believe it would appeal to the public, split the Tories and end the loss of English Labour voters to UKIP.

It would also, of course, raise the difficult question of which leader posed the biggest risk to Scotland's place in the EU - Ed Miliband, David Cameron or Alex Salmond?

Perhaps it's significant that the shadow cabinet's most senior Scot, Douglas Alexander, is among those who are unconvinced by the plan.