Ed: The Milibands and the Making of a Labour Leader, By Mehdi Hasan & James Macintyre

O brother,wherefore art thou?

There was a line in 25-year-old Ed Miliband's eulogy at his father Ralph's funeral in 1994 where the son told how the Marxist academic used to make up bedtime stories for his beloved boys about two sheep on the Yorkshire moors, named Boo-Boo and Hee-Hee.

It is a touching moment, revealed in this first, unauthorised biography of the Labour leader, but also one that invites the reader to look for the hidden meaning. Were the two sheep Ed and his older brother David? If so, is David Boo-Boo, the still-sulking loser of last year's leadership contest, and Ed Hee-Hee, the winner?

The desire to look, in hindsight, for clues as to why Ed Miliband, putting personal ambition over family loyalty, would challenge his brother's presumed succession to the Labour leadership, is strongly felt throughout Ed, by the authors, Mehdi Hasan and James Macintyre, and reader alike.

Ed, five years younger, is constantly shown in David's shadow. David gained a First in politics, philosophy and economics from Oxford; Ed followed his brother to Corpus Christi college, also to read PPE, but dropped philosophy and failed to get a First. Ed and David remained close, but the authors say that the age gap and, later, working for Gordon Brown and Tony Blair, respectively, meant that they operated in different circles. Did this distance make it easier for Ed to commit "fratricide"? Ed is sometimes the "friendly Brownite" but elsewhere shows "genuine ruthlessness" in his political dealings.

The authors have amassed a level of detail which, especially during chapters covering the well-trodden ground of the Blair-Brown wars, doesn't always seem necessary. And while the book is titled Ed and not "Ed and David", it misses an opportunity to go into more of the older brother's, equally compelling, story. But passages about the Milibands' family life are genuinely moving: the parents' escapes from the Nazis, Ralph's tenderness for his sons and, during last year's contest, the despair of their mother, Marion Kozak.

Ed is a broadly sympathetic portrayal, yet Hasan and Macintyre prefer an analysis of why Ed "did it" which fits the current Westminster "Cain and Abel" narrative, rather than simply accept that he felt he deserved to run. Some Labour figures resentfully ask the "why" question because Ed hasn't yet shown he has the qualities to become Prime Minister. Perhaps by the time the paperback is out, he will have.

Jane Merrick is the Political Editor of The Independent on Sunday