International Co-op day? never heard of it until I read this post.

The definition of a cooperative in Wikipedia is a legal entity owned and democratically controlled by its members

I have never seen one formally set up as a cooperative. Most, while technically unincorporated societies with a constitution and officers to satisfy the requirements of a bank account, seem to be run by a largely self appointed formal or informal group consisting of the very few who can be bothered to get involved with day to day organisation.

If the club works, most people seem happy to let the organisers get on with it.