IF you thought that 2015, with its surprise general election result, was a big year for politics then hold on to your hats – 2016 could be even bigger.

That’s because this year we will be facing probably the most important political decision of our lifetimes – whether or not Britain should remain a member of the European Union.

Irrespective of the rights and wrongs of our membership of the EU, and whatever the result, the referendum will have a major impact on the main political parties.

While it’s true that Labour has its own Eurosceptics, the party facing the biggest divisions over Europe is the Conservatives. However the decision goes, there will be enormous consequences for the party.

Most smart money is on David Cameron claiming to have won sufficient concessions from his European partners to enable him to declare that he has secured a good-enough deal for him to campaign for a Yes vote.

But no matter what concessions the Prime Minister wins, they are unlikely to satisfy those in his party who want the UK to leave the EU.

If Cameron is able to convince a majority of the British people to vote Yes, then his Eurosceptic colleagues will be, to put it mildly, angry. And with a majority of just 12 seats over all the other parties, they could make his life in Parliament very difficult indeed – just ask John Major.

On the other hand if Britain votes No then Cameron will surely have to step down immediately. The resulting leadership contest could be bloody indeed, especially because a significant number of Conservative MPs will see Cameron’s campaign for a Yes vote as a betrayal and the result as a disaster for the country.

Whoever wins the referendum, because Cameron has said that he will not be leading the Tories into the next election, 2016 could well see a Tory leadership contest.

The current leading candidates are Chancellor George Osborne, London Mayor Boris Johnson and Home Secretary Theresa May, with Osborne the bookies’ favourite.

Or maybe there’s a dark horse lurking – a Jeremy Corbyn figure that no one predicted as the next leader– quietly biding his (or her) time.

Talking of Europe, it could be that because of the EU referendum Ukip risks sliding off the political map into irrelevance.

This is partly because if Britain votes to leave the EU, it will have lost its main reason for existence and if Britain votes to stay, it might well appear dated and irrelevant.

That’s not to mention the damage being done to the party by the continued feuding between leader Nigel Farage and Ukip’s only MP, Douglas Carswell.

But when it comes to inner-party feuding, Labour beats Ukip all ends up. Party leader Jeremy Corbyn might not face a major Euro-problem now that he has accepted that Labour will campaign for a Yes vote but that is the least of his problems.

No leader of a modern political party has faced Corbyn’s situation – backed by the overwhelming majority of party members but by fewer than one in 10 of his MPs.

There are bound to be constant murmurings by his colleagues against his leadership and maybe even an attempted coup.

Corbyn might hope for a boost in May when Labour’s Sadiq Khan battles with the Tories’ Zac Goldsmith to be London mayor but even victory in the capital might not keep the Labour hounds at bay.

For Corbyn 2016 could be make or break. The same might be said for the United Kingdom itself, if not in the coming year then in the not-too-distant future.

For in May there will be elections for the Scottish Parliament and if, as predicted, the SNP surge continues then renewed demands for Scottish independence are bound to be heard again – particularly if the rest of the UK has voted to leave Europe.

Given the small Conservative majority in the Commons, the 54 Scottish Nationalist MPs and Conservative Eurosceptics, bitter about the outcome of the referendum, could make life very difficult indeed for Mr Cameron or his successor – so difficult in fact that he (or she) might just be tempted to give the Scots another vote to settle the independence question once and for all.

If that goes ahead the result this time round could well see a majority voting for independence.

Then we would face the next New Year with Britain out of Europe and Scotland out of Britain. As I said – a big year for politics.

  • Ivor Gaber is a former Westminster correspondent and now Professor of Journalism at the University of Sussex