Just as in the UK the market was soon dominated by major companies but instead of the initials being GNER or LNR the Spanish ones were TBF (Tarragona, Barcelona, Francia), MZA (Madrid, Zaragoza, Alicante) and Ferrocarriles Andaluces (Andalusian railways.) Just like in the UK the fat years were followed by thin and a quango, the EFE, Explotación de Ferrocarriles por el Estado, was formed in 1926 to bring some order to the system and to keep lines open. In 1941 EFE was divided in two. RENFE, Red Nacional de los Ferrocarriles Españoles, took all the wide gauge network leaving EFE with a mish mash of five different gauges from 750mm to 1.435 metres. RENFE is still the main, state controlled rail operator but, since 1992 it has split into two arms - one is based on the traditional Spanish gauge but their high speed trains, the AVE, run on the standard European gauge. Spain currently has the second longest network of high speed routes in the World and within a couple of years it will have moved into first place.
As time went on and more lines and companies ran into financial trouble EFE took them over. Eventually, in 1965 some attempt was made to rationalise the system and FEVE, ferrocarriles de via estrecha, was formed. I think, though I'm not certain, that as a part of that rationalisation FEVE only took on lines based on the 1 metre gauge. Most of the key lines that FEVE operates are in the North of Spain and most have a history related to transporting goods, for instance coal from mining areas to iron and steel smelting regions. FEVE does, however, operate 19.5kms of track running from Cartagena to Los Nietos. Apparently the line was built between 1874 and 1897 by first British and later Belgian companies to serve the local silver, lead and iron mines. That line ran from Cartagena to Los Blancos but when mining slumped in the first quarter of the 20th Century the line was taken over by the state in 1931. In 1972 the line was born again, converted to the standard 1 metre gauge (it had been 1.067 metres) and the stretch from El Estrecho to Los Blancos being abandoned with a new terminal in Los Nietos opened in 1976.
I know that trains arouse certain passions amongst certain people so I apologise now to those people who found my shortened, and probably partially inaccurate, version of the history of the Spanish railway systems infuriating - the trouble is that axle configuarations just don't do it for most people!