Iberian broad gauge is used in Portugal too.
The new high speed lines in Spains were mainly built to standard gauge. Some Talgo trains have variable axles so they can run on both standard and Iberian gauge. The technology has been there since the 1960's when the first Catalan Talgo trainsets were introduced with a gauge changing facility near Port Bou (Spanish/French border). The original Catalan Talgo ran from Barcelona to Genève. Later is was cut to Montpellier where a change to the TGV is provided.
What the article misses are the different loading gauges even if the rail gauges are the same. The British loading gauge means that trains are narrower and lower than in continental Europe. No doulbe decker trains in the UK therefore.