If you´re let go after working on a contract as pensioner, you´re not entitled unemployment benefits ´paro´ or unemployment subsidy ´subsidio´ if you´re already in receipt of a full contributive state pension, but the upside is that if you informed the INSS correctly when you began working as pensioner, you weren´t charged the ´paro-component´ of the social security contributions either.
If you were in receipt of a UK pension, this wasn´t cut while you were working, but if in receipt of a Spanish contributive pension, the status quo (March 2018) is that you were cut 50%, so when your job ends, you will be able to receive 100% again, but no ´paro´ unemployment benefits on top of that.
If you didn´t have enough work history to be entitled to a contributive state pension, but were receiving or would now be entitled to a non-contributive pension instead, you will still be able to claim and enjoy your full paro entitlement first.
Info from Employment Agency Website.