Tomorrow an earnest 40-year-old man will speak to the nation as the new leader of HM Opposition, writes John Hipwood.

It will be billed as the most important speech of his life, but if he tells us again how much he loves his older brother, an agonised scream will reverberate around the land.

Amazingly, the Labour Party has managed to elect the younger Miliband, Ed, rather than David as their new leader.

It’s true to the party’s recent form in such matters: Gordon Brown – loser; Ken Livingstone (as London Mayoral candidate) – loser; Ed Miliband – who knows? But David Cameron will have let out a sigh of relief on Saturday, probably followed by a self-satisfied chuckle.

True to his form, the Prime Minister swiftly issued a statement congratulating the winner, and he will no doubt do the same when he faces Mr Miliband across the Commons dispatch box when Parliament gets back to business in a fortnight’s time.

“I was leader of the opposition for four years and know what a demanding but important job it is. I wish him and his family well,” said Mr Cameron, probably thinking of David Miliband in those last seven words.

How different it was back in 1994 when an earnest 41-year-old was elected leader of the Labour Party. I doubt that John Major smiled at the thought of Tony Blair challenging him for his job.

With Gordon Brown famously standing aside following their ‘deal’ in an Islington restaurant, who remembers now whom Mr Blair beat in the contest to succeed the late John Smith?

For the record, it was John Prescott and Margaret Beckett.

In 16 years’ time, both Ed and David Miliband will have been pushed to the far recesses of our memories if Labour loses the next general election. But in the meantime, what a story the brothers have produced for us.

A friend said to me on Saturday evening that if a novelist had submitted a manuscript telling such a tale of filial political warfare, publishers would have sent it back by return of post.

That Ed should have challenged his elder and far more experienced brother was incredible enough in the first place. For him to have set up his campaign so ruthlessly to come through and win by a nose was even more unbelievable.

Ed knew from the start that he could not possibly win if he simply looked like a younger version of David, so he unashamedly targeted Labour’s core vote, successfully winning the backing of the unions.

It was illuminating that the first three emails I received congratulating Ed M on his victory came from Unison, Usdaw and Unite.

This strategy meant that the tag ‘Red Ed’ was attached to the shadow energy secretary rather than the shadow education secretary, who stuck religiously to the distinctive Ed Balls agenda.

During the campaign, Ed M. didn’t worry too much about the label, but now that he’s won, he realises it’s time to discard it — and fast. “All these accusations about Red Ed are both tiresome and rubbish quite frankly,” he told Andrew Marr yesterday.

He denied he wanted to take his party to the left, repeatedly insisting that he was “the change Labour needs”, without actually spelling out what that change would mean. Mr

Miliband did, however, reject the advice of Labour core hate figures Blair and Peter Mandelson by insisting that the era of New Labour was past.

Just 12 months ago Lord Mandelson was the hit act at Labour’s conference in Brighton.

“A new generation has taken over and it’s not about the old labels any more,” said the new leader.

David Miliband wasn’t happy to be seen as the New Labour flag carrier either, but at least he stuck to his principles during the campaign, refusing to suck up to the unions or to deny responsibility for Labour’s mistakes, including the 2010 manifesto, which, incidentally, his brother wrote.

The new Labour leader would have us believe that he did not talk to his brother in their conversation on Saturday evening about David’s future and what job he would be prepared to accept in the shadow cabinet. He preferred to hide behind the fact that, under Labour’s crazy constitution, the party’s MPs choose the members of the shadow cabinet, leaving the leader to allocate the jobs from the names announced on October 7.

It is, of course, unthinkable that the MPs, having put David well ahead of Ed as their leadership choice, would not elect him to the shadow cabinet.

But, more to the point, which job would he want to do? Does he really want to carry on as shadow foreign secretary, having been the actual foreign secretary? Anything less than shadow chancellor would look like a demotion, and the non-job of deputy leader has been astutely secured by Harriet Harman.

It would be wiser for David M to get out now and go and earn his living elsewhere.

In the meantime, we’ll all watch with the keenest interest the new Leader of the Opposition’s big speech tomorrow. Watching very closely will be John Culshaw, Rory Bremner and Alistair McGowan.

At last the impressionists, in despair at not being able to pin down David Cameron and Nick Clegg, have the opportunity to mimic a party leader with a distinct adenoidal voice.