Spanish time (GMT+01:00) is notionally one hour ahead of the UK - but conceptually Spain might as well be on a different planet. Nowhere in Europe keeps such late hours. Spaniards may not take a traditional midday siesta so much as they used to, but their life cycles remain committedly nocturnal. They'll saunter out around 8pm or 9pm in the evening for a paseo , to greet friends and maybe have a drink and tapas, and if they're eating out, they'll commonly start at 10 or 11pm, sometimes later in Madrid. It's not unusual for someone to phone around midnight to see if you're going out for the evening.
Like everything else, Practices differ somewhat by region. Madrid is famed for staying up the latest, with Andalucía a close second. In the north, particularly in Catalonia, they keep more Northern European hours. And, of course, summer nights are the real late, late shows.
Read more about the Siesta in Spain