Tre nel Mille (1971) credited, as Knight. Originally released theatrically in 1971, this was later shown in a greatly expanded six-part TV mini series version titled Storie dell'anno Mille in 1973. That's the version I watched. Geoffrey appears in episode 2 of the mini series version. I don't know how much - if anything - that remains of his performance in the theatrical cut...
Pane e cioccolata (1974) credited as Geoffrey Copplestone, as Mr. Boegli, the restaurant manager. Here, Geoffrey has a minor role as a Swiss character, and from this point onward, he would be cast more and more frequently as either Germans, Frenchmen, Russians etc.
Il portiere di notte (1974) credited, as Kurt. Geoffrey has just a minor role as one in the group of former SS men in this highly controversial film by Liliana Cavani. He does, however, get to appear in the film's most (in)famous and iconic sequence, when Charlotte Rampling is dancing and singing for her Nazi captors while wearing pieces of an SS uniform.
Salon Kitty (1975) as Dinner guest. After Il portiere di notte, Geoffrey appeared in another film that was a progenitor to the short-lived Nazisploitation fad, though his role is no more than a little cameo.
A Matter of Time a.k.a. Nina (1976) credited, as Hotel manager. This American film shot in Italy was the last film directed by the famed Vincente Minnelli, and Geoffrey has a pretty good role here, getting to appear in a couple of scenes together with Ingrid Bergman, Liza Minnelli and Charles Boyer.
Il genio a.k.a. Le grand escogriffe (1976) as Foreign aristocrat. He's not credited in French-language version that I have, but is supposed to be in the Italian, though his role is very small...
Emanuelle e gli ultimi cannibali (1977) credited as Geoffrey Coplestone, as Wilkes. Just a short role for him as Monica Zanchi's father in this violent entry in the Emanuelle series, and once again he speaks his own voice in the English-dubbed version.
Napoli si ribella (1977) credited as Joeffrey Copleston, as German boss. Just a short role for Geoffrey in this Eurocrime movie, but it's worth noting that he actually dubs his own voice (with a German accent) for the Italian-language version. It's the earliest film where I've found him dubbing himself in Italian. He does, however, not dub himself for the English-language version, which is actually one of the worst dubs I've ever heard!