Now you might we wondering why Berwick should appear in this list, but it has an interesting history. It's been swapped between Scotland and England throughout the years.
The Berwick-upon-Tweed entry on the Wikipedia has the following detail - Since Berwick had changed hands several times, it was traditionally regarded as a special, separate entity, and some proclamations referred to "England, Scotland and the town of Berwick-upon-Tweed". One such was the declaration of the Crimean War against Russia in 1853, which Queen Victoria supposedly signed as "Victoria, Queen of Great Britain, Ireland, Berwick-upon-Tweed and all British Dominions"
the Treaty of Everlasting Peace [between Scotland and England in 1502] stated that Berwick was of England but not in England, so Berwick was always mentioned separately in Acts of Parliament. - read more at www.culture24.org.uk
So I don't count Berwick as a country, but I do claim it as an honourable mention in my travels.