Pretty sidelock.
The I 2 date code is 1989. That matches Terry Wieland's chart for Grulla serial numbers as 1990 ended at 31,276
Certainly looks like Eibar Spain Proofs for a 3 inch chamber 20 gauge with Grulla's logo. Chopper lump barrels, gas escape valve bushed firing pins (strikers). Purdey style rose and scroll engraving like a Grulla 216.
But a single trigger model which is no doubt a custom order and not typical of the double trigger with articulated front trigger.
I believe American Arms imported a Grulla made SLEs.
https://www.shotgunworld.com/bbs/viewtopic.php?t=173093 I suspect the Churchill reference on the barrels is actually a model designation of a Churchill type gun of 25 inch barrel length with a narrow but tall tapered center rib a la Robert Churchill's London made side by sides known as the Churchill XXV. You do not mention the barrel length in your post so maybe i am wrong on that.
My guess is it is a 5 pin sidelock design like the Grulla 216 and not a 7 pin Holland and Holland design as in the Grulla Royal range.