I am Spanish, and grew up very close to the region (C.Valenciana), and love the region, so it hits close to home, I wrote 3 different replies specifically, but then realised, I am only going to get more pissed off. I will only reply, the coverage carried out by the British newspapers at the time was incredibly poor, so I hope that wasn’t your source of information.
To those asking, why are some people in Catuluna desperate for independence? Its simple, money. The supporters of this movement do not want a part of the income they generate to go to the most disadvantaged areas and would rather keep it to themselves. Many of the top supporters of this movement are wealthy Catalans waiting on being able to dig in more. They’ve been indoctrinating the region for the past 20 years, changing school content and textbooks in order to achieve this. ….and you thought Brexit was bad. Yes there are other reasons such as regional identity and central government mismanagement(money again), and they are I see the point of anger, since my region too has been hit by questionable central government policies, however an ILLEGAL referundum and unconstitutional unilateral independence declaration(however short this declaration lasted) is not the way.
Why was the referendum illegal? There was no agreement between central government and regional government on how to carry it out.