The conviction of Andy Coulson last week left an open goal for Labour. I choose my words carefully, given that Coulson is about to face a retrial on further charges, but Labour was – and still is – quite right to question the judgement of David Cameron for hiring Coulson as his communications director.

Seven years after the scandal first broke it’s easy to forget that Coulson was hired in May 2007, just four months after he had resigned as editor of the News of the World following the conviction of its royal editor Clive Goodman and private investigator Glenn Mulcaire for phone hacking. Even in 2007 the “rogue reporter” defence was wearing thin. As a father (and a former journalist) I am as sickened as anyone that any reporter should hack into the mobile phone of a murdered teenage girl, and that any editor condoned or encouraged the practice.

But shooting at an open goal should not invite charges of time-wasting or unsporting behaviour. Labour should let the conviction speak for itself, and move on.

It was a mistake  for Ed Miliband to ask so many questions at PMQs on June 25th about the security vetting that Andy Coulson had or had not received: as the Guardian‘s John Crace has argued, if there was an open goal Miliband missed it. Although no Labour spindoctor was ever convicted of any crime, its record on spin and toadying to Murdoch make Labour vulnerable on the issue and Cameron saw Miliband’s questions coming from a mile off.

In any case vetting is a red herring. In 2007 you did not need security vetting to discover that Andy Coulson had already been questioned over phone hacking: just Google. Security vetting is designed to find anything in your private life that could be used to blackmail you. But concerns about phone hacking at the News of the World were anything but private – they had been all over the media for months before Andy Coulson was hired by David Cameron in 2007. Unless there is a sensational revelation yet be made about Andy Coulson, I can’t see how security vetting would have made any difference to his appointment.

This isn’t the first time that Labour’s message has been blunted by irrelevant distractions. And this is not just Ed Miliband: the leadership is the least of the party’s problems. Leaving aside Labour’s stance on intervention in Syria (opportunism according to some critics) the opportunism is often most apparent on the backbenches or in the back rooms of Brewer’s Green, not on the frontbench. Too often, Labour is trying to grab headlines at random, crying wolf and diluting its message. Too often, Labour backbenchers make pious demands for public enquiries or resignations, or issue attention-grabbing announcements that don’t hold water.

In the space of just a few months in 2013, John Mann MP called for a police enquiry into Lord Hanningfield’s expense claims, an investigation into an alleged child sex ring in Lambeth (where Mann was a cllr in the 1980s) and made an embarrassing blunder by accusing European Commissioner Laszlo Andor of being a member of the anti-Semitic Hungarian party Jobbik (Andor is, in fact, a member of the Socialists). He also asked the Lib Dems to explain why Mike Hancock MP was allowed to continue as a senior councillor in Portsmouth even though he had resigned the Lib Dem whip in parliament to fight allegation of sexual misconduct in the civil courts (Portsmouth is 200 miles from John’s Bassetlaw constituency).  In September 2012 John Mann had called for Sir Irvine Patnick, Tory MP for Sheffield Hallam when 96 Liverpool fans died at the FA Cup semi-final at Hillsborough stadium in April 1989, to be stripped of his knighthood for his alleged role in covering up the role of the police in the disaster. Patnick died a few months later, making the request redundant, but the incident left a nasty taste in the mouth. Is it really the role of a Labour MP to demand that former MPs are stripped of their knighthoods even though they have not been convicted of any crime?

More recently, Luciana Berger’s complaints about rising gym membership costs made the party look opportunist , or at worst, amateurish and out-of-touch – exactly the sort of charges we are levelling at the Tory-Lib Dem coalition. At a time when many people can’t afford to pay their food and housing costs, gym membership is the last thing on their minds.

This silliness is a pity as it distracts from the excellent work that many Labour MPs and shadow ministers are doing to highlight issues that really do matter – Stella Creasy’s campaign against legal loan sharks, for example. These should not be drowned by the white noise of opposition.

Just as some Labour MPs have been increasingly scatter-gun in their attacks on the Coalition, the party has become over-sensitive to media banter. Labour, as always, will get an unfairly hard time from the right-wing newspapers between now and the election, but we should not cry wolf in advance.

In September 2013 Rachel Reeves was called “boring snoring” by Newsnight Editor Ian Katz  after an appearance on the programme (he thought his tweet was a personal message, not going to all his 26,000 Twitter followers. He now has 32,000 twitter followers, which shows there is no such thing as bad publicity). Rachel Reeves seemed to take this on the chin and recognised that a Treasury minister being called a bit boring is probably no bad thing – a “boring” media appearance means no rash spending commitments, no statistical howlers, no contradicting other ministers.

But the reaction of the party itself was shrill and petty:  Katz received an email thundering “It is completely unacceptable for a senior BBC editor to have expressed this view, whether or not you intended for it to be made public. It is vitally important that the Labour Party, our Shadow Cabinet and Newsnight viewers have confidence in the impartiality and fairness of your programme, and the criteria on which guests and interviews are judged…. Although a tweet of apology has been made, a full written public apology should be made by the end of the day.” Politicians lecturing journalists about impartiality is a bit like King Canute ordering the tide to stop coming in: it doesn’t work, and it can get you into deep water.

I wish John Mann and other MPs of his ilk would concentrate on the job they do best between now and May 2015 – representing their constituents. As for the Shadow Cabinet, they should remember that the next general election will be  decided on how confident voters are about the economy and how competent the party leaders are seen to be, not who did or did not give security vetting to Andy Coulson four years ago.

Understatement works.  If Labour needs to put out a press release saying “a disastrous week for George Osborne”, as they did last November,  we can be sure that Osborne has actually had a pretty good week – otherwise there would be no need to point out how bad it was. If there’s nothing useful to say, a period of silence from the party’s media machine would, to misquote Clement Attlee’s famous putdown of Harold Laski, be most welcome.

It’s the old showbiz adage: Show, don’t tell. If the Coalition government really is incompetent, wrong-headed and out of touch – and it certainly is all three of these things – then this should be plain for voters to see by May 7th 2015. If the British people vote the Tory-Lib Dem coalition out of office next May – as I hope they do – it won’t be because Ed Balls has told the Today programme how awful they are every day.

In the 1990s Labour benefitted from the tidal wave of Tory sleaze without having to do much work of its own. Many of the stories that came to light – Tory MPs receiving brown envelopes full of cash in return for asking questions in parliament – couldn’t have been made  up. For once they did not need any spinning.

The last four years have shown that Labour, and Ed Miliband, are at their best when they act unexpectedly and bravely, rather than reaching for the convenient stunt or soundbite. The phrase “at our best when at our boldest” may not have resonated much when Gordon Brown was in Number Ten , but it certainly is true now.

Ironically, it was the phone hacking scandal that prompted one of the defining moments of Ed Miliband’s leadership: who could have predicted that he would call the bluff of Rupert Murdoch and call for the closure of the News of the World? But there’s now a good case for just sitting back and seeing what happens – not taking to Twitter at every sign of Coalition disarray, or jumping on every passing bandwagon with a press release. Focus relentlessly on what really matters: public services, the economy and the cost of living. And remember: show, don’t tell.

New Labour or Old Labour are both fine – but let’s avoid Opportunistic Labour.