The decision by the London mayoral candidates to publish details of their earnings and tax will have caused some anxiety among other British politicians. An established practice in America, it has yet to catch on in the UK, where even the idea of televised election debates was seen as a radical departure.
But, if at the next general election candidates feel bound to release their own tax returns, they will have Green party mayoral candidate Jenny Jones to thank. Her call on Newsnight for everyone to reveal all, cleared the air around a story that has lingered smog-like over this election.
The claim that Ken Livingstone used a limited company in order to avoid paying tax has continued to dog the Labour candidate, largely because he has allowed it to. Had Ken been totally open about his tax affairs a month ago, we could now be talking about the issues Londoners really care about.
Instead he has let the story drag out, even choosing to sling similar allegations back at Boris Johnson during a live radio debate. The resulting row in a lift in which Boris repeatedly called Ken a "fucking liar" only prolonged Ken's problems, while convincing many Londoners that neither candidate really has our best interests at heart.
After this low point, the agreement on Newsnight was a chance for Ken to finally put it all behind him. But in yet another unforced error, he seemed to wriggle out of his commitment, saying he would only reveal all if the other candidates also released details of their partners' incomes to an independent body.
This was not what had been agreed. So when the other candidates simply released their own tax returns to the press, Ken was left looking like he had something to hide. When he finally did release some information, key details were missing, ensuring that the story simply rumbles on for another week.
In Boris's case, we now know that his hard-fought campaign to get his personal rate of tax reduced from 50p will save him about £16,000 a year if he is re-elected. A Tory mayor reducing his own tax bill by £16,000 while cutting everyone else's tax by just £3 would have been a powerful line of attack for a Labour candidate – especially as Boris continues to raise fares well above inflation. Unfortunately for Ken, he now has little hope of successfully making this attack.
But what this week has really shown is that modern elections are becoming increasingly dominated by issues of personality rather than policy.
On policy alone, Ken should be well ahead of his rival. One recent poll showed that Ken's policy of cutting fares was the most popular with voters, while Boris's policy of a small cut to council tax was the least popular. Ken's other pledges on a "living rent", lower energy bills, childcare costs, and student finance also cover issues most Londoners say they care about.
Boris's pledges, on the other hand, are a confusing mixture of things he falsely claims to have already done and unexciting promises for more "street trees" and an "Olympic legacy". If the election is about policy then Boris knows he might lose. If the election is about personalities then he knows he will probably win.
For this reason the mayor's allies have relentlessly pursued the tax story to the point of outright fatigue. Like those in the US who spent years demanding that Barack Obama release his birth certificate, their real goal has not been to see the documents themselves, but to distract the public from the real issues.
And the truth is it is working. Ken has allowed himself to be distracted from his campaign, Boris has been allowed to get away with achieving very little and promising even less, and the big issues that London faces over the next four years have barely had a look in.
Ken only has himself to blame for his difficulties. But the success of the campaign against him is just one more step in the gradual Americanisation of British politics. And with public tax returns and televised debates imported, it surely can't be long before the requests for politicians' medical records begin.
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