Should Pays De Galles be Au or Aux.

Question

I thought plural countries were aux so should it be 'aux Pays De Galles' instead of 'au Pays De Galles' or does Pays De Galles count as singular since it means Wales.

Accepted Answer

James - it is singular - le Pays de Galles. Hence ' au Pays de Galles'. 
"Pays" is the same spelling in plural and singular. 
Les Pays-Bas (the low countries), as 'Netherlands' was originally a number of different countries/jurisdcitions, but le Pays de Galles (the country of Galles) as it is 'one country'.
 https://progress.lawlessfrench.com/revision/grammar/using-le-la-l-les-with-continents-countries-and-regions-names 
https://www.wordreference.com/fren/pays