That's because there is a slight, but important, difference in the thinking behind public holidays in the two countries. In one the idea is of a holiday entitlement and in the other the idea is that there should be a rest from work on a festive day. In England, each year, you get eight extra days holiday, on top of any work related holiday entitlement. If a public holiday happens to fall on a Saturday or Sunday then you will get the previous or the next working day off as a substitute. In Spain if the festive day falls on Saturday or Sunday then it simply disappears from the annual holiday calendar because work won't get in the way of you celebrating that day.
So, why is it that there seem to be public holidays all the time in Spain if the real difference is just a couple of days? One of the reasons is for the way that the Spanish territory is organised. We need to remember that Spain, the state, is made up of regions and municipalities. All three of those entities affect the holiday calendar. The state can set up to nine days of public holiday, the regions set three and the municipalities, two.
We'll get to the national holidays in a while but let's start with the municipal, the local, days off. Pinoso (the picture is the Pinoso flag) is a good example. It borders five other municipalities (Yecla, Jumilla, Abanilla, Algueña and Monóvar). All six of those municipalities get to choose two local holidays, nearly always based on some local tradition. It's more than likely that when Pinoso has a day off the other five won't. When people hardly ever left their home town this was hardly a problem but, nowadays, we often cross municipal borders to go to work, to use a gym or to do the supermarket run. That being the case you can easily find yourself caught out and come to the conclusion that Spain is always closed.
Now to the regional days off. Three of the municipalities bordering Pinoso are in the Region of Murcia. Each region has a regional day and each one is different. So when Valencia celebrates the anniversary of the taking of Valencia city from the Moors in 1238, on 9 October by Jaume I, Murcia will be hard at work. On June 9 on the other hand the Murcianos may well be wearing alpargatas and zaragüelles to dance in the street to celebrate the adoption of their most recent boundary changes while we Valencianos grind through the daily routine.
Another regional variation comes from the so called replaceable days. To get to these we need to talk about the national holiday calendar, días no laborables. Central government produces an annual list of public holidays. There can be up to nine. New Year's day, Good Friday, Labour Day (May 1st ), Assumption Day (August 15th), National Day of Spain (October 12th), All Saints Day (November 1st), Constitution Day, (December 6th), Immaculate Conception (December 8th) and Christmas Day (December 25th). If any of those dates falls on a Sunday they will not be included in the list for the year. As well as these days the government publishes, each year, a list of suggested days for public holidays. Remembering that regional governments can set up to three days off the regions may adopt some or all of these replaceable days. If they wish they can make regional substitutions. When different regions make different replacements this causes another variation. To give a concrete example one of the replaceable days suggested by the national government is the Thursday of Holy Week, Maundy Thursday in old money (see the quip?). The Murcia Region likes that and takes the Thursday. On the other hand the Valencian Community has a tradition of celebrating the Monday of Holy Week instead. Murcia's plan produces a long weekend before Holy Week and Valencia's a long weekend after Holy week, a Monday off that Britons often, wrongly, confuse with the English Easter Monday.
The days on that replaceable or changeable list always include January 6th, Epiphany, the day after the Three Kings bring Christmas gifts for children in Spain, the Thursday before Easter Sunday and San José or Fathers Day on March 19th. There are usually a couple of other suggestions which vary from year to year. None of those days will be a Sunday. That doesn't mean that some Sundays will not be celebrated as festive days. Easter Sunday is, a good example, as is Mother's Day which is always the first Sunday in May. Both are recognised festive days, in the same way as they are in England but none of them need to feature on workday calendars as Sunday is always a day off.
It's a system that lots of Britons find hard to get to grips with while Spaniards like the way it honours local differences and traditions.