Relief for Ed...but just what will David do next?

And so after all the hoo-ha, a relatively easy win for Labour and a creditable second place for the Liberal Democrats, with Nick Clegg's party staving off the post-tuition fees meltdown some had feared.

Both Mr Clegg and Labour's Ed Miliband went into Thursday's Oldham East and Saddleworth by-election on something of a hiding to nothing - but both appear to have got away with it.

Instead, it is Prime Minister David Cameron who may have the most difficult questions to answer after appearing to soft-pedal the party's campaign in the final week.

After their party's share of the vote was more than halved while the Lib Dems' went up, Tory backbenchers already unhappy about the direction of the government will want to know why their coalition partners were given such an easy ride.

For Mr Miliband, a result which saw Labour's majority increase from 103 to 3,558 will take the pressure off – for now.

After a decidedly lacklustre start to his leadership, Mr Miliband moved to sharpen up his press operation in the weeks before Christmas and this appears to have had pretty instantaneous results.

Victory in what was already a Labour-held seat should leave little room for complacency, however.

His appointment of the economically sub-literate Alan Johnson as Shadow Chancellor appears to be unravelling, while his own appearance on a Radio 2 show a couple of weeks back ended in embarrassment, with Middle England listeners quizzing him over his unconventional private life.

The by-election also saw a fleeting return to the political fray for elder brother David Miliband, one of 40 Labour MPs who travelled to the constituency on Thursday for some frantic last-minute door-knocking.

It concluded what to say the least has been an eventful week for the South Shields MP, with his surprise appointment as vice-chairman of Sunderland Football Club.

At the same time, reports emerged that he was being lined-up a possible new role as a TV presenter with the BBC.

Cynics might be tempted to pose the question: What next? An appearance on 'I'm a Celebrity, Get Me Out of Here' maybe?

In fairness to David, he has made clear his intention to continue as a constituency MP at least until the next election, while in an interview with this newspaper before Christmas, he signalled that he has still not given up hope of leading the Labour Party one day.

He has also appeared to set out his stall as a backbench 'Voice of the North' – although his new role at the Stadium of Light scarcely seems designed to endear him to all corners of the region!

But taken together, the two stories highlight the difficulties which can face politicians when they lose their main raison d'etre – climbing the greasy pole.

And while he is not about to join the 'Z-list' of those who are famous for being famous, Mr Miliband needs to give careful thought to what he does next if he is to remain a serious political player.

The prospect of him becoming a TV presenter inevitably drew comparisons with Michael Portillo – and not for the first time.

Mr Miliband's somewhat cack-handed attempts to unseat Gordon Brown in autumn 2008 echoed Mr Portillo's botched coup against John Major in the summer of 1995 when his supporters were caught installing phonelines for a leadership campaign HQ.

Mr Portillo was regarded by many in the Conservative Party as its natural leader, but partly through circumstance and partly through lack of judgement, he ultimately became its lost leader.

There are many still hoping that David Miliband, so long seen as the 'heir to Blair,' can avoid a similar fate.

One of them, possibly both, is going to end up a loser

Given that the British electorate as a whole only gets to vote once every 4-5 years, it is perhaps inevitable that by-elections tend to wield a somewhat disproportionate influence on our political process.

Usually they follow a fairly predictable pattern. The public – or the media – identifies which of the two main opposition parties is most likely to give the governing party a good kicking, and the 'protest vote' does the rest.

But we are in unchartered waters now. There are two governing parties, only one main opposition party, and the new-ish leader of that party is something of an unknown quantity to most voters.

All of which is what makes Thursday's Oldham and Saddleworth by-election possibly the most fascinating such encounter since the Darlington contest of 1983 which, to Labour's ultimate detriment, saved the leadership of Michael Foot.

On the face of it, it ought to be plan sailing for Labour. In a few short months, the Con-Lib coalition has slashed public spending, put up VAT, and scrapped much of the regional aid budget that was helping former industrial towns like Oldham to find a new role.

Not only that, but the seat was won by Labour in the general election last May, before MP Phil Woolas was disqualified from Parliament for having lied about his Lib Dem opponent on his election literature.

One of the many imponderables in this contest is whether the fate of Mr Woolas will help or hinder Labour's cause here.

The fact that he was actually quite a popular local MP might appear to favour the party, but some voters may feel he was too readily hung out to dry by the Labour establishment, and punish the party accordingly.

Inevitably given its status as a three-way marginal, 'Old and Sad' is being viewed as something of a mini-referendum – not just on the Coalition, but on Labour leader Ed Miliband.

If Labour cannot even win by-elections in seats it already holds, serious questions will start to be asked as to whether it can win anywhere else under Mr Miliband's leadership.

But for Lib Dem leader Nick Clegg, too, a defeat on Thursday would be seen as a significant blow.

His party's candidate, Elwyn Watkins, may well feel the seat is his by moral and indefeasible right having been on the wrong end of Mr Woolas's misdemeanours, but politics doesn't work like that.

Undoubtedly the leader with the least to lose and the most to gain here is Prime Minister David Cameron.

For one, the Conservative candidate Kashif Ali started the contest in third place. For another, the Tories have been accused of soft-pedalling their campaign in a bid to help their Lib Dem partners.

Perhaps realising he is in with an outside chance of a stunning victory Mr Cameron is now doing his best to dispel that impression, becoming the first premier to campaign in a by-election for 13 years.

Yet ironically a Tory win, in a seat where the Lib Dems began as the main challengers, might end up being more destabilising for the Coalition than a Labour triumph.

Mr Clegg would then face more tough questions from his own activists and MPs as to what exactly the Lib Dems are getting out of the Coalition.

A Tory victory would simply reinforce the idea that it is the Lib Dems who are taking all the political pain while Mr Cameron reaps the political dividends.

But whoever wins on Thursday, at least one and possibly both of Mr Cameron's fellow party leaders are going to be waking up to some difficult headlines on Friday morning.

And for either or both of them, that could set the tone for a tricky political year ahead.

Why 2011 is the Coalition's make-or-break year

Two weeks ago I concluded my review of the political year 2010 by posing a question which will, in my view, determine how the next 12 months in British politics ultimately pan out.

It was: can the Coalition government as a whole withstand the dramatic loss in popularity suffered by the Liberal Democrats since their decision to go into partnership with David Cameron’s Tories.

As Ricky Ponting can no doubt testify, a team is only as good as its weakest link, and with public support for the Lib Dems now barely registering in double figures, Nick Clegg’s party are clearly the weakest link in this government.

The big question for Mr Clegg is how much lower he can afford to allow that support to drop before continuing membership of the Coalition simply becomes politically unsustainable.

If any further proof were needed of the Coalition’s inherent instability, then the Vince Cable affair in the run-up to Christmas surely provided it.

There were several ironies about this episode, not least that a newspaper which shared Dr Cable’s hostility to Rupert Murdoch’s takeover of BSkyB managed to shoot itself so comprehensively in the foot.

But surely the biggest irony of all is that, for all the humiliation he heaped upon himself, Dr Cable turned out to be correct in his estimation that he was, in effect, unsackable.

Whatever you think of the methods used to ‘entrap’ him, any other minister who displayed such appalling naivety and lack of judgement would surely have been out of the door.

But because Mr Cameron dare not weaken the Lib Dem element of the Coalition for fear that the whole edifice will collapse, he survived - thought not without having his wings severely clipped.

So much for the events of the week before Christmas. What of the year ahead?

Well, since this is traditionally the time of year for crystal ball gazing, I’ll make a prediction. If the Coalition gets through the next 12 months, it will more than likely achieve its ambition of serving a full five-year parliamentary term.

Why is 2011 likely to prove the Coalition’s make-or-break year? Well, for starters, it is likely to become significantly more unpopular as the cuts bite, unemployment continues to rise, and the full implications of some of its more radical experiments become clear.

I have in mind here Andrew Lansley’s NHS reforms and Michael Gove’s de-municipalisation of schools, neither of which can claim much of a popular mandate.

But the biggest single threat to the Coalition’s survival is the time-bomb that is due to detonate underneath it on Thursday 5 May – the referendum on the alternative voting system.

If, as many now expect, the referendum is lost, it will remove the Lib Dems’ main incentive for having entered the partnership in the first place.

For Labour leader Ed Miliband, too, this will be a critical 12 months, as he seeks to demonstrate to a sceptical public why he, and not his elder brother, is the right man for the job.

At least he now has a clearer opposition strategy, seeking to brand this a Conservative-led government supported by reluctant Liberal Democrats rather than the marriage of true minds Messrs Clegg and Cameron would like to portray.

Yet for all that, Mr Miliband is probably no more keen to bring the government down right now than Dr Cable: his party is broke, he hasn’t had time to overhaul the policies that lost it the last election, and the public doesn’t really know him.

If the Coalition does manage to survive the year, it might simply be because none of the three main parties really wants to have another election just yet.