There seems to be some confusion about which cards apply to which circumstances.  As I understand it, the E111 was replaced by the EH1C.  This was issued by the UK and was to cover emergencies whilst travelling abroad.  It provides reduced cost and possibly free treatment including that for pre-existing conditions.  It does not cover travelling abroad for specific treatment or for repatriation.  It is valid for five years and can be applied for or renewed on line.  THis is obviously appropriate for holiday makers and probably is adequate for people with property in Spain but who do not live here full time.
For those who live here full time, there are two appropriate documents depending on age.  For those under 65 (i.e. not in receipt of a UK state pension), the document is the E106 which provides the same benefits as those enjoyed by Spanish residents.  It is however only valid for two and a half years and if that expires before you retire, you're on your own for the remaining time.
If you are in receipt of a pension the the E121 comes into play and again gives you entitlement to the same treatment as the Spanish.
Applying for it is no mean feat.  I went through the rigrmarole after obtaining my green Certificate of Residency.  I eventually got a letter from Tarragona which seemed to translate (via Google) that I merely had to take it to my local health centre to be issued with a Tarjeta Sanitaria Individual (TSI).  Apprently not so.  The local health centre told me that the letter merely confirmed that I was now registered with the Spainish (or Catalan) Social Security system and that I would have to apply for the card with all the usual bumph (NIE/passport, letter, Padron (flippin pain as they only last three months)) etc. etc.  That's where I'm at at the moment.  This is only my own understanding and I stand to be corrected if I'm wrong.