Bicentennial Enamelware

These six cups were for sale on an internet site, much like ebay, but Spanish and for collectors. The seller had posted two, and when I bought them both, he mentioned he had more. After a little haggling, I got all six for 38€, shipping included. What these babies were doing in Santander I have no idea.
They are too chipped to use, but are so incredibly 70s!!
They are quite large, easily holding a US pint, or 1/2 liter of liquid.

They look Bicentennial to me, but maybe someone out there knows more? I've googled them and come up with nothing!
The seller only knew that they had been found in an old farm in a village in Cantabria (northern Spain) ---of all places!!!!

An older friend told me they appear to be just some patriotic cups that were left over from some function..but what???
Any info on the maker, age and what they were doing in Spain, would be greatly appreciated.