Tim Roth portrays Archibald Cunningham the man who causes most of the troubles for old Rob Roy. Roth makes no excuses about it from his opening scene that Archibald is the villain of the film. A cockney and overly prim villain with his gloating smile, and fancy boy manner. Roth aside from one very brief moment does not show Archibald to have any sympathy for his completely amoral actions. He is the bad guy plain and simple who does not mind for a second his murdering of Rob Roy's friend, stealing his money, burning his house, and even raping his wife.
Roth certainly has basically the same style throughout as he goes from scene to scene being evil, and acting like a pompous pretty boy well he does it. Roth is most certainly consistent and has the right sort of slimy charm in the role. He is fairly imposing as a villain, and he becomes most certainly worthy of hate so when he and Rob Roy clash swords you certainly want him to meet the business end of Roy's weapon. Roth is as he should be as Cunningham conniving and cruel, and is an effective enough villain.
The only problem I have with the performance though is he is just not that memorable of a villain in the end. He is a good enough villain as the film runs its course but soon after watching it I do not remember his performance that well. Villains commonly are the type of characters that can become unforgettable, but although I would not say Roth's Cunningham is forgettable he just is not one I would ever be quick to say he is an antagonist for the ages, rather just a suitable enough antagonistic.
Roth just stays consistently villainous throughout the only moment where he shows a different side of Cunningham is an extremely short one where he indicates he actually has some regret over one of his immoral acts. It is a small silent reaction but it is actually very well handled by Roth suggesting that maybe deep in Cunningham's pompous exterior there is not such a horrible man there somewhere. The scene is short but well done, but it really is not brought up past this short moment. In the end this is just a fine villain performance not ever amazing but never bad either.