WHAT do Andy Murray, the hero of the moment, and Len McCluskey, the grumpy boss of the trade union Unite, have in common?

Not much, obviously enough – apart from the fact that they are both currently, and no doubt unintentionally, performing the role of God's gift to David Cameron.

I'm sure David Cameron was every bit as sincere in his delight as Alex Salmond, sitting behind him, was when Andy Murray swept to victory at Wimbledon on Sunday. No doubt part of Mr Cameron's very political mind was calculating that a Murray triumph would add to the feel-good factor which is starting to be talked about as the UK enjoys a glorious July.

At least one poll has suggested that a majority of British people are, for the first time in years, allowing themselves to be a little more positive about their financial future. Add that positivity to some sunny weather and a few sporting spectaculars, and everything begins to look rosier for the Coalition, and the Tories in particular.

But I'm sorry, Mr Cameron: it's not as simple as that. I cannot see the UK's economic situation improving as long as we remain import junkies, recklessly importing so much more than we export. And anyway, even if the UK economy does recover somewhat, and thus benefit the Coalition, that would actually pose a big problem for Mr Cameron. If he sincerely wants to maintain the Union, paradoxically the last thing he needs is a continuation of the current tentative recovery for the Tories in the opinion polls, for that would undoubtedly prompt many Scots currently expecting to vote No in next year's referendum to have second thoughts.

I'd also advise Mr Cameron to be cautious in trying to exploit Labour's undoubted current difficulties with the Unite union. Mr McCluskey – recently re-elected as leader of Unite in a vote in which the turnout was less than 20% – does represent a considerable problem for Ed Miliband. He also represents an opportunity: Mr Miliband should be using the ongoing debacle at Falkirk to press for serious union reform. Nobody with any responsibility should be pressing for union obliteration.

Although I place myself slightly to the right of centre, I'm ultimately more relaxed with a political party that is funded by the workers – as Labour essentially is, despite all the problems at local level in constituencies such as Falkirk – than a party that is funded by megawealthy individual donors. There is still a need for trade unions in Britain, and there is nothing wrong with them having direct links with the Labour Party, as long as individual unions don't get above themselves and act as the bullying masters of a weakened political party.

A little-noticed development in recent trade union history is that union membership has begun to rise, albeit slightly, among private sector workers. This is encouraging; many of the poorly-paid workers in the private sector have a real need for effective, responsible union representation. Paradoxically, at the very time when the unions are unfortunately associated in the public mind with brutish power broking of the kind that was all too prevalent in days gone by, union members in the past decade have been just as likely to be well-paid professionals in the public sector as poorly-paid workers in the private sector.

Of course there's not necessarily anything wrong with that, except that these poorly-paid private sector workers are in rather more immediate need of effective union representation. So the current balance in the trade union movement should continue to be recalibrated, and I'm sure Ed Miliband realises that.

Such matters are very distant from the euphoria which can be so spectacularly ignited on the tennis court (or the rugby field, far away). Well done, Andy Murray; but I'd point out that Len McCluskey, for all his faults, has many more people to look after and fight for than Andy Murray does.

I just wish that Mr McCluskey went about his enormously important job in a more gracious and considered way.