The Banco Occidental was founded in 1964 and was headquartered in Madrid. It experienced significant growth and became part of the Spanish banking scene of the time. In the early 80s, due to a financial crisis, the Deposit Guarantee Fund had to intervene and it ended up being acquired by Banco de Vizcaya in 1982, one of the predecessors of the current BBVA.

Thanks to this box, I found another collector but of calendars, a "story seeker" like me who coincidentally has some calendars from Banco Occidental. I noticed a lot of similarity with the 1978 calendar in terms of typography, design, and especially in the lime green tone. I would bet that my box is from that year.