The Banco Occidental was founded in 1964 and was based in Madrid. It experienced considerable growth and became part of the Spanish banking landscape 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 have found another collector but of calendars; he is a "story seeker" like me who happens to have some calendars from Banco Occidental. I have seen a lot of similarity with the 1978 calendar in terms of typology, design, and especially, in the lime green tone. I would bet my life that my box is from that year.