Kalbo. I would suggest the best place to answer your question is theSpanish consulate in Cyprus.
Mike and Jean. My nephew is British and has an Amerian wife. Getting into the UK was causing grief due to her US passport, particularily as they live in Valencia. She now has a Spanish ID card to travel to the UK on it and so I guess the same rules will apply to your wife and there will be no problems. Apart from dealing with the beaurocrats.
Sorry but I am confused about this reply:-
A USA national I believe can visit UK without a visa, so your wife having a ‘Spanish ID card’ as you call it, although I think you mean Residencia, does not affect that, as she would travel as USA national, thus I believe her status as Resident in Spain is irrelevant.
I believe , “had no problems with obtaining the residence permit in Spain” is nowhere near as simple as that may imply. She would still have to follow the same procedure as any other citizen from outside the EU.
Traveling to UK using one’s ‘Residencia’ status in an EU country is not always as straightforward as you imply, even following the ECC finding in the McCarthy case :-(http://curia.europa.eu/jcms/upload/docs/application/pdf/2014-12/cp140182en.pdf)
My wife is Filipino, resident in Spain for coming on 10 years, and BA will still not let her board a flight to UK without a visa.