Professor Alan Matthews:

Yes. This is something we will need to explore further now that we have a little more clarity on Britain's objectives. If they said they would stay in the customs union, that particular issue might have been less urgent. There are some important agreements, including the Good Friday Agreement, which in a sense give us something to build on. Currently, I have difficulty in trying to conceive exactly how that might work in practice as I know how European Union trade policy works vis-a-vis third countries. It is a well established regime. There is the idea of trying to see bits of a country having a different regime from the United Kingdom and how it might work. There are precedents, although not very convincing, and we may be able to build on them. We have the example of Greenland and Denmark but this will require much more work and thought now that we know what-----