We did have this actor identified as Andrew Hughes, who is listed in this role by IMDb.
However, having found this actor also in
Segretissimo…
I looked more closely at Hughes and from images online I don't think the actor above is him, while facially similar Hughes has more hair on top and clearly different ears, meaning he is now unidentified in both films.
Since both Crack in the World and the scene where he appears in Segretissimo were shot in Spain then the actor who appears in both films was presumably Spanish, or at least based in Spain.