Il treno per Istanbul (1980) (TV mini series). I've not been able to find this TV mini series, but according to the listing in Radiocorriere TV, he plays the role of Sir Arthur and is credited as Geoffrey Coplestone.
L'avvertimento (1980) credited, as District attorney. A good role for Geoffrey, who brings a lot of gravitas to his character, even if he just appears in a few scenes, and as usual, he dubs himself for the English version. Not for the Italian dub, though.
L'uomo puma (1980) credited as Jeffrey Coppleston, as Sir George Bradley. Another very short appearance, and yet again we hear Geoffrey's own voice in the English dub but not in the Italian one.
Razza selvaggia (1980) credited, as Marco. This is one of Geoffrey's sleaziest roles, and there's even a scene where he tries to force a young girl to give him a blowjob in the back of a car!
S+H+E (1980) credited as Geoffrey Copplestone, as UN speaker. Geoffrey gets another typical one-scene role in this American-German production shot in Rome, and since it was shot with live sound, we of course get the pleasure of hearing his real voice.
Bianco, rosso e Verdone (1981) as Russian diner in restaurant. A little uncredited cameo for Geoffrey in this very famous comedy. It's one of several times where he plays a Russian, and he even dubs his brief dialogue with a convincing Russian accent.
Black Cat (Gatto nero) (1981) credited, as Inspector Flynn. Geoffrey appears in a couple of scenes near the end of this Lucio Fulci horror movie. Not surprisingly, he dubbed his own dialogue for the English dub.
Bollenti spiriti (1981) credited, as Steiner, Nicole's husband. A little larger than usual role for Geoffrey in this comedy as the jealous and suspicious husband of Lia Tanzi. He again dubs his own voice for the Italian version.
Don Luigi Sturzo (1981) (TV mini series) credited, as Cardinal Bourne. Yet another time where Geoffrey only appears in a single scene, but at least he speaks his own dialogue in Italian.