Dr David Shiels is a Policy Analyst at Open Europe and also works on contemporary political history.

If the Conservatives are returned with a majority in December, the next phase of Brexit will become a reality very quickly. Having secured a mandate for his deal, Boris Johnson will lead the UK out of the EU in a matter of weeks. Although the Conservative manifesto pledges to negotiate a free trade agreement to ‘strengthen our union’, there has been little debate about what strategic choices would serve the best interests of the UK as a whole.

While a closer relationship with the EU might now be the preference of the Unionists in Northern Ireland, there will be other pressures pushing the Government towards a basic free trade agreement, or even towards a WTO-terms exit. For the nationalist parties in Northern Ireland and for the SNP in Scotland, the lack of a UK-wide mandate for Johnson’s deal will present a new opportunity to exploit anti-Westminster sentiment.

The first and most obvious challenge for the Government in the next twelve months concerns the operation of the Northern Ireland Protocol, which is more complicated than the original backstop. The DUP and other Unionist parties are concerned that the East-West checks envisaged in the Protocol are going to be cumbersome, vindicating their fears about a ‘border in the Irish Sea.’ Their concern is shared by business leaders in Northern Ireland who – though they see the Johnson deal as preferable to a No Deal Brexit – are worried about the timescale involved in implementing the new arrangements. They have questioned how the Government will deliver its pledge to maintain ‘unfettered access’ to the market in Great Britain.

Ministers have not helped the situation by offering contradictory statements about whether exit declarations will be needed for goods moving between Northern Ireland and Great Britain, while the Conservative manifesto offers no detail on this point. These are ultimately decisions for the specialised committee which oversees the implementation of the Protocol, and there is an onus on the UK Government to ensure that the interests of business in Northern Ireland are well represented.

The second concern is whether Northern Ireland will be able to benefit from future UK trade deals with the rest of the world as the Prime Minister claims and as is promised in Article 4 of the Protocol. In practice, a lot will depend on how the Joint Committee interprets the provision in Article 5 to establish criteria for judging whether goods coming from Great Britain are “at risk” of being moved into the EU. Again, the UK will need to ensure there is input from politicians and business representatives at the appropriate Committees.

To this end, the UK’s bilateral relationship with Ireland is vital. As the Government belatedly learned after the referendum in 2016, Ireland saw Brexit as a key strategic challenge and made a huge diplomatic effort to safeguard its national interests. In the end engaging with Dublin was the key to the Brexit deal. After months of political stalemate over the original Withdrawal Agreement, Boris Johnson’s one-to-one meeting with Leo Varadkar paved the way for the revised Protocol. Both leaders have an interest in making it work; and both Governments must hold the EU to its commitment to ‘protecting the Good Friday Agreement.’

There is also an essential common interest between the Irish Government and the Unionists in Northern Ireland in minimising disruption to West-East trade and in making the agreement work for the benefit of the people of the whole island. The Republic could serve as an important ally for the UK as it seeks to negotiate a trade agreement – although the UK will have to work hard to make its own case with other EU members.

Ultimately, the question of whether the deal will work for Northern Ireland comes back to its internal politics. Following a very bitter general election campaign there, the chances of an early return to power-sharing at Stormont seem low – although Julian Smith hopes for some ‘Christmas spirit.’ Much depends on the performance of the two main parties and whether they want to face the electorate in another Assembly election early next year. A concerted effort on the part of both Governments will be needed to restore a sense of stability while a return to direct rule, possibly with an Irish dimension, cannot be ruled out. This will raise serious questions about the viability of the consent mechanism envisaged in the Protocol.

The functioning of the Protocol also links back to a wider point about the future of the Union and the relationship between Northern Ireland and the rest of the UK. Some business leaders believe the deal could still offer Northern Ireland the ‘best of both worlds’ with access to the markets in Great Britain and the EU. But this has always been a problematic argument for Unionists, because it celebrates potentially permanent divergence between Northern Ireland and the rest of the UK.

Persuading them to embrace the new settlement will be difficult. The Government has also been wary of making a virtue of special treatment for Northern Ireland because of the UK-wide implications of the policy. The SNP has stopped short of making a major political issue out of special treatment for Northern Ireland – thanks to gentle interventions by the Irish Government – but the potential for mischief-making on this question remains.

In recent years, the Scottish Conservatives have embraced devolution as enthusiastically as their Unionist counterparts in Northern Ireland. But – as a glance the Scottish Conservative manifesto reveals – there is a tension between the promise of ‘sweeping new powers’ after Brexit for the Scottish Parliament and the party’s commitment to ‘maintain UK-wide approaches’ in certain areas, particularly in relation to protecting the UK’s internal market. Already the SNP has accused the Government of staging a ‘Westminster power-grab,’ while it will be alert to any possible ways of influencing or frustrating the UK Government’s efforts to negotiate free trade deals with other countries.

One area where the Conservative manifesto jealously guards Westminster’s powers is over immigration policy – an area where both the SNP and the Northern Ireland parties have been at odds with Westminster. The Scottish manifesto claims that the devolution of immigration would lead to a ‘border at Berwick’. But there are challenges in making a London-based policy work for all parts of the country, as witnessed in the response to the £30,000 minimum salary threshold for skilled migrants recommended by the Migration Advisory Committee. In developing a new immigration system there could be ways to seek the input of the devolved administrations.

Finding a way through these issues in a way that is consistent with the party’s other pledges on Brexit will be a key challenge next year if a Conservative Government is returned. In the words of the Scottish manifesto, the party needs to be prepared to ‘think strategically’ about the future of the Union after Brexit.