Was it ETA or someone more synister?

Either way I think it is useful for the Spanish authorities to use it to swing public opinion behind them for any actions that they've seen as necessary but unpopular for a while.

More worryingly is the list of places targeted. Any obvious omissions so far?

Britain must be prepared: both to thwart any similar attempts and to deal with the aftermath. More to the point Britons must be resilient and prepared. We must be prepared to cope with such tragedy and to meet the enemies of our society and civilisation head-on. We must also develop a will of iron and nerves of steel to pursue the course and values which we know are right. We should not be cowed by cowardly threats and blackmail but must defiantly continue our daily lives to show this dark danger that we will never let it triumph.