Britain goes to the polls on June 23 to determine whether it is to remain part of the European Union. Prime Minister David Cameron has secured what I believe is a good deal for the United Kingdom from his EU partners who, without doubt, understand the importance of Britain staying in the bloc.

Britain’s membership of the EU has now been redefined and voters are being given a once-in-a-lifetime opportunity to either approve this new arrangement or to opt to leave the Union permanently. It is a crucial referendum, one that will decide what type of country Britain wants to be. The vote will also have implications for the entire EU as well as for the future of the UK as a unitary State.

Mr Cameron’s deal includes an ‘emergency brake’ on migrants’ in-work benefits for four years, an exemption for the UK in the EU’s bid for ‘ever-closer union’, a reduction in benefits for children of EU migrants living overseas, protection for the City of London and no discrimination for British businesses for being outside the eurozone. Hopefully, the curbs on migrants’ benefits will go some way in allaying voters’ concerns about EU migration into the UK, mainly from Eastern Europe, which is probably the ‘No’ camp’s most powerful argument.

The official position of the Conservative government is to approve this new package and to keep Britain in the EU. Members of the Cabinet, however, are allowed to campaign, in a personal capacity, for either side in this referendum, showing just how divided the Conservatives are over Europe. The majority of Mr Cameron’s Cabinet ministers are backing him, including key figures such as George Osborne, Chancellor of the Exchequer, Theresa May, Home Secretary, Michael Fallon, Defence Secretary, and Philip Hammond, Foreign Secretary.

Six Cabinet ministers, including Justice Minister Michael Gove, have announced they will campaign for Britain to leave the EU, as has popular London mayor Boris Johnson, who no doubt is planning to replace Mr Cameron as Conservative leader and Prime Minister should the ‘No’ camp win the referendum. One hundred Conservative MPs (out of 331) have already said they will campaign for a ‘No’ vote, and how the Conservative electorate votes will determine the outcome of this referendum.

The Labour Party, the Liberal Democrats, the Scottish and Welsh Nationalists, the Greens, the SDLP and Sinn Fein (both Northern Ireland parties) are in favour of Britain remaining in the EU. The UK Independence Party and the Democratic Unionist Party (Northern Ireland) want Britain to leave the EU. The Ulster Unionist Party (Northern Ireland) has not yet taken a stand.

Roughly speaking, the pro-EU parties at last year’s general election received 48.3 per cent of the national vote, the anti-EU parties received 13.2 per cent and the Conservative Party received 37 per cent. Theoretically, if half the Conservative voters back Britain staying in the EU (I don’t expect a higher figure than that), then the ‘Yes’ camp should win the referendum, but this will only happen in a scenario where the large majority of those who voted for the pro-EU parties last year will vote ‘Yes’.

If you want to run Europe, you must be in Europe. If you want to be run by Europe, feel free to join Norway

I have no doubt, however, that there will be some left-wing voters among Labour and even perhaps among the Scottish Nationalists who will vote for Britain to leave the EU.

So I think the vote will be close, but there is no reason why the ‘Yes’ camp should not win, especially if it runs a campaign in simple, understandable language which stresses the economic and security advantages of remaining in the EU, as well as the fact that Britain in the EU plays an important role on the global stage.

This should be contrasted with the uncertainty and the huge risk associated with a so-called Brexit, where there is no Plan B, and which would be nothing but a leap in the dark. Hopefully, the ‘Yes’ campaign will include people from all walks of life, not just politicians, but businessmen, trade unionists, environmentalists, people in the arts and culture, former members of the military, security experts, economists and former diplomats.

People thinking about voting ‘No’ should contemplate one of the likely consequences of a Brexit which would be the break-up of the country. The Scottish government has already said that a ‘No’ vote in the UK, against the wishes of Scotland’s voters, would trigger a new referendum on independence. I am sure that under such circumstances Scotland would indeed vote for independence, which might possibly even encourage Wales to think about seceding.

This is something UK voters should think about very seriously. Just imagine what reduced influence and clout on the global stage a rump State of England and Northern Ireland – outside the EU – would have. And just imagine how Nationalists in Northern Ireland would react to Britain leaving the EU; such an outcome could well derail the province’s peace process and cause tensions between Nationalists and Unionists. One of the reasons why the peace process has been largely successful is the fact that both the UK and the Republic of Ireland are in the EU, and this has greatly helped reduce sectarianism.

The economic case for Britain staying in the EU will probably be a determining factor in the referendum campaign. Numerous studies have stated that economic growth would suffer should the UK leave the EU and that membership of the bloc had benefited the British economy. Thousands of jobs depend on the UK having access to the Single Market and the very high level of foreign direct investment into the UK owes a great deal to the country being part of the EU. London, for example, owes much of its success as the financial capital of Europe precisely because of Britain’s EU membership.

Those who argue that Britain would still have access to the Single Market as a non-member should realise that this would take ages to negotiate, leading to a great deal of uncertainty, and if such an agreement was ever reached, Britain would have to pay dearly for such access and would still have to obey the rules – without having any influence whatsoever in making them. Furthermore, access to the Single Market would have to include the free movement of people, something both Norway and Switzerland have had to accept. As a Norwegian minister said: “If you want to run Europe, you must be in Europe. If you want to be run by Europe, feel free to join Norway.”

And what about the EU’s 53 trade deals, which Britain would no longer be part of should it leave the bloc? Would Britain be able to re-negotiate such free trade agreements? And would countries like India, China, the US and South Korea be interested in spending so much time and energy on negotiating a deal with Britain, or what’s left of Britain? There is certainly no way the negotiating clout of a Britain out of the EU could remotely be compared to the collective clout of the EU.

Another strong argument against Britain leaving the EU is that this would severely weaken the bloc, which is the last thing the EU needs at the moment when it is faced with so many crises. The EU’s role in global diplomacy, such as facing up to an increasingly assertive Russia or negotiating a nuclear deal with Iran, would be weakened in the event of a Brexit. So would the fight against terrorism, as EU co-operation in security, judicial and police matters plays an important role in this area.

The bloc’s foreign policy and security clout would also be diminished after losing its biggest military power. Furthermore, Britain’s voice in the EU in favour of competitiveness, free trade, less regulation and less federalism would be greatly missed if the UK left the bloc.