Free Radical, By Vince Cable

At times of crisis, Britain needs political heroes, epic figures to guide it through the wreckage and towards a more hopeful future. In the 1940s Churchill played the role of the great titan. After the war Attlee and Bevan became heroic figures. In the late 1970s enough of the country turned to Margaret Thatcher to ensure she won a series of landslide general elections.

And in the midst of the most serious economic crisis since the great depression of the 1930s, Vince Cable is the country's god-like guide. Polls suggest Cable is more trusted and respected on the economy than any other politician. Cable speaks and a nation listens.

Perhaps the most spectacular manifestation of his new stardom was the bestselling success of his book on the economic crisis, The Storm. For a book by the Liberal Democrats' Treasury Spokesman on a crisis of multi -layered complexity to make it into the charts was another extraordinary twist in the late-blooming career of a previously obscure, self-effacing politician.

Cable is a good journalist and writes accessibly. As he notes in this autobiophy, he has learnt the art of writing quickly and to tight deadlines. He writes weekly columns, delivers speeches, gives interviews, and presumably prepares for an election campaign in which he will feature almost as prominently as his leader, Nick Clegg.

Not surprisingly, Cable's publishers wanted a follow-up book as quickly as possible. In the light of his deification a memoir must have seemed the obvious course. Why not write a book about Cable?

The answer is not as straightforward as it seems. While Cable has said much of interest over the last two years, he is not an especially interesting politician. This is not his fault – or at least he is culpable only in the sense that he chose to join a party doomed to eternal opposition. Previous political heroes played a defining role in government. Cable has led a more tranquil political life.

Indeed, that he has become a hero from the safety of the opposition benches is a reflection of our anti-politics age. On the whole the decision-makers are despised: those who worked through the night to devise rescue packages for banks and a fiscal stimulus for the economy. Cable, who put his case from a safe distance, is the hero.

Much of his case was audacious and sound, but it is much easier to display such qualities when they are not being put to the test around the clock. Ultimately the memoirs of Brown, Darling, Mandelson and Balls will be incomparably more interesting.

Cable implicitly acknowledges the limits of his political journey by admitting that he wrote this book in the hope that it might be of some interest to his family. He also chooses to be more constrained by skipping over the few moments of political drama in which he has been involved. I have been intrigued by his involvement in the fall of his previous leader, Ming Campbell, since listening in disbelief to an interview with Cable on Radio 4's The World at One during autumn 2007. In the space of a few minutes he had subtly placed a knife into the back of his leader. Within hours, Campbell had resigned. Perhaps the two events were not connected.

Disappointingly, there are no definitive answers here. Cable writes about the resignation of Campbell briefly and as if he was an outsider rather than a player of some significance.

There is also only a fleeting reference to his leadership ambitions. Probably this is a truthful account. Cable triumphed as a politician when it was too late. His star rose as acting leader, with other candidates in a leadership contest. Perhaps if the contest had followed Cable's moment in the leader's spotlight, he might have stood and won. But the tone is not regretful. He is much more popular and authoritative than he would have been had he become a party leader, where I suspect anti-politics cynicism would have started to count against him.

Cable might be a beneficiary of the anti-politics culture but he is highly political. The most vivid sequence in the book follows his tortuous path to becoming an MP, a route that highlighted the tensions on the centre left in the 1980s and the degree to which it can be wretchedly difficult to win a seat. Cable was a Labour supporter and close to John Smith, whom he still describes as his political hero.

But he gave up with Labour in the early 1980s and joined the SDP, contesting York in the 1983 election. He lost in spite of the energetic support of the SDP's stars who came to campaign for him. It took another 14 years before he finally entered the Commons as a Liberal Democrat.

Cable has led a full and surprisingly eventful life. All that is lacking is a phase in power. For a political memoir, it is quite a gap.