[Joppa]

Since you are in Spain on the basis of Spanish immigration law, your residence card isn't regarded as issued under Article 10 or 20, so you need EEA family permit to enter UK.
Does your card actually state “Residence Card of a Family Member of a Union Citizen”?
https://www.gov.uk/government/publi...as-the-holder-of-an-article-10-residence-card

 

[Joppa]

I have merged your two threads. Please don't open another on related topic.
I think your residence card is no longer valid as you and your EEA partner have left UK.
Your Spanish residence card may be regarded as Article 10 RC if you came to Spain under Surinder Singh provision following a spell living in UK, where your partner was exercising EU treaty right.

 

[Joppa]

So you can't use your UK residence card (expired by now) but if you presumably entered Spain under Surinder Singh, your Spanish residence card is Article 10 RC so can be used to enter UK without visa or EEA family permit. The words 'Family member of an EEA citizen' on your card are crucial. Read the link above.

 

[Joppa]

But as the Spanish residence card says family of EEA national, it must have been issued under Surinder Singh provision of EEA reguations and not under Spanish domestic law. The importance here is the residence card becomes Article 10 document and the OP can enter UK without EEA family permit or UK visa.