The Diary: The taxing problem that Livingstone just can't shake off

London mayoral candidate Ken Livingstone (PA)

Ken Livingstone pulled level with Boris Johnson in the London mayoral contest at the start of this year when a fares hike took effect, but lately he seems to be looking for ways to throw the election away.

His difficult relations with London's Jewish community are reported on our news pages today, but the issue which has given Johnson back his lead appears to be Livingstone's tax arrangements. While he was out of office, Livingstone had his accountant arrange for his earnings to be channelled into a private company to avoid the 50p top tax rate.

Other people do it, but they have not castigated tax dodgers the way Livingstone, pictured, has. It is an open goal, of which David Cameron took full advantage during Prime Minister's Questions yester- day. It's not the first time that Livingstone's penchant for putting his earnings into a private company has made the news and therein lies a heavy irony.

Twelve years ago, he decided to stand as an independent against the official Labour candidate for which he was expelled from the Labour Party. On the day he was expelled, a damaging story appeared in The Times suggesting that Livingstone had broken the law by taking money out of his private firm to finance his political activities.

This story – in contrast to the current stories about his tax affairs – was Labour friendly. Its author was the Times journalist, Tom Baldwin, now Ed Miliband's senior media adviser. The source of his information was possibly not a million miles removed from Labour Party headquarters.

Is Danny going cuckoo?

On the BBC website there is an enlightening recording of Danny Alexander, Chief Secretary to the Treasury, being interviewed about reports that the Government was thinking of removing the 50p top rate of tax.

"It's something that we as Liberal Democrats pushed very hard for that the Government's first priority in tax reductions would be people on low and middle incomes. We are going to lift the income tax threshold to £10,000. The idea that we are going to somehow shift our focus to the wealthiest in the country at a time when everyone is under pressure is cloud cuckoo land," he vouchsafed.

Yesterday, Mr Alexander was to be seen sitting alongside his boss, George Osborne, just like a cuckoo in a cloud.

Alan Turing – a hero of note

Three months tomorrow will be the centenary of the birth of Alan Turing, the mathematician who broke the Enigma code, thus hastening the Allied victory in the war, for which the state rewarded him by forcing him to undergo chemical castration because of his homosexuality. Obtaining a posthumous pardon for Turing is proving impossible, so someone has had the idea of putting a petition on the Downing Street website calling for Turing's face to be put on the £10 note. It attracted 1,500 signatures in double-quick time.

Scoops and changing times

In 1983, The Guardian published an exclusive about nuclear weaponry based on a document leaked by a civil servant. When the police came looking, the paper's editor, Peter Preston, surrendered the photocopied document, an act which unintentionally led to the arrest and imprisonment of the leaker, Sarah Tisdall. Preston was widely condemned and has not been allowed to live the incident down.

More recently, the police demanded to see an email exchange between Isabel Oakeshott, political editor of The Sunday Times, and Vicky Pryce, estranged wife of Chris Huhne. The emails were handed over, after brief resistance, and Pryce now awaits trial.

At Tuesday night's press awards ceremony, The Sunday Times was shortlisted for an award for its coverage of the Huhne-Pryce case, and Isabel Oakeshott was named Political Journalist of the Year. Times have changed.