What is Calan Mai?
Calan Mai is the Welsh name for Mayday, a festival held on 1st May, you can read more about Mayday here & here and about the history of Calan Mai here & here. 1st of May is also International Workers Day. You can read the history of that here, here & here.
Mayday events happen all around the world, there is scarcely a capital city in Europe without a MayDay parade, Cardiff is notable for not holding a regular event.

May 19, 2008 at 2:35 pm
Despite my preferring Swansea, of course I will support.
Best wishes.
Gethin.